According to Michael Porter, the threat of substitution, is a function of three factors:
* The relative value/ price of a substitute compared to an industry's product
* The cost of switching to the substitute
* The buyer's propensity to switch
(Porter, Michael E.. Competitive Advantage: Creating and Sustaining Superior Performance (p. 278). Free Press. Kindle Edition.)

Every sector among the options requires intensive capital investment. However, only manufacturing and retails bury much of their working capital in form of inventory. Raw materials and WIP only present in manufacturing sector.
The manufacturing industry is undergoing massive change, rivaling the Industrial Revolution that began in England and continued on Detroit's assembly lines. But today's revolution is "smart," thanks to factories using artificial intelligence and robots.
A new trend is the "cobot" - a collaborative robot designed to work with humans. One company called Moduform uses them to make furniture in the U.S. The company credits using cobots for reducing their staffing turnover, since the robots do mundane repetitive tasks that bore humans, while people can now do cognitive tasks requiring judgment and diversified responsibilities. Other innovations include 3D printing, Artificial Intelligence and automation.
Today's artificial intelligence manufacturing revolution improves performance in two key areas of manufacturing: productivity and quality control.

Overhead variances arise when the actual overhead costs incurred differ from the expected amounts.
Managers want to understand the reasons for these differences, and so should consider computing one or more of the overhead variances described below. Each of these variances applies to a different aspect of overhead expenditures. It is not necessary to calculate these variances when a manager cannot influence their outcome.
Fixed Overhead Spending Variance
The fixed overhead spending variance is the difference between the actual fixed overhead expense incurred and the budgeted fixed overhead expense. An unfavorable variance means that actual fixed overhead expenses were greater than anticipated. The formula for this variance is:
Actual fixed overhead - Budgeted fixed overhead = Fixed overhead spending variance The amount of expense related to fixed overhead should (as the name implies) be relatively fixed, and so the fixed overhead spending variance should not theoretically vary much from the budget.
Fixed Overhead Volume Variance
The fixed overhead volume variance is the difference between the amount of fixed overhead actually applied to produced goods based on production volume, and the amount that was budgeted to be applied to produced goods. For example, a company budgets for the allocation of $25,000 of fixed overhead costs to produced goods at the rate of $50 per unit produced, with the expectation that 500 units will be produced. However, the actual number of units produced is 600, so a total of $30,000 of fixed overhead costs are allocated. This creates a fixed overhead volume variance of $5,000.
Variable Overhead Efficiency Variance
The variable overhead efficiency variance is the difference between the actual and budgeted hours worked, which are then applied to the standard variable overhead rate per hour. The formula is:
Standard overhead rate x (Actual hours - Standard hours)
= Variable overhead efficiency variance
A favorable variance means that the actual hours worked were less than the budgeted hours, resulting in the application of the standard overhead rate across fewer hours, resulting in less expense being incurred.
However, a favorable variance does not necessarily mean that a company has incurred less actual overhead, it simply means that there was an improvement in the allocation base what was used to apply overhead.
Variable Overhead Spending Variance
The variable overhead spending variance is the difference between the actual and budgeted rates of spending on variable overhead. The variance is used to focus attention on those overhead costs that vary from expectations. The formula is:
Actual hours worked x (Actual overhead rate - standard overhead rate)
= Variable overhead spending variance
A favorable variance means that the actual variable overhead expenses incurred per labor hour were less than expected.
In the study guide, CIPS splits overhead variance into volume and expenditure variance. They can be understood as variable and fixed overhead variance respectively.

In the scenario, ABC Ltd has the following characteristics:
- Large investment in facilities and machinery
- Access to skilled workforce
- Mass production.
This company is a manufacturer. Manufacturing is an industry that makes products from raw ma-terials by the use of manual labour or machinery and that is usually carried out systematically with a division of labour.
Manufacturing requires investment in machinery and access to a suitably skilled workforce as well as materials and components.
Reference:
- CIPS study guide page 74-76
- manufacturing | Definition, Types, & Facts | Britannica
LO 2, AC 2.1