An incident is any event that occurs during testing that requires investigation. An incident management tool is a software tool that supports recording and tracking incidents throughout their life cycle. A QA manager of a start-up company needs to implement within a week a low cost incident management tool. The best option for this case is to manage the incidents in a spreadsheet posted on the intranet. This option has several advantages over other options:
It is low cost, as it does not require purchasing any additional software or hardware.
It is easy to implement within a week, as it does not require installing or configuring any complex software or hardware.
It is accessible and transparent, as it can be viewed and updated by anyone who has access to the intranet.
It is structured and organized, as it can store and display various information about incidents, such as identifier, summary, description, severity, priority, status, resolution, etc. The other options are not suitable for this case, as they have several disadvantages over the chosen option:
Documenting incidents on a large board in the lab is not a good option, as it is not accessible or transparent to anyone who is not physically present in the lab. It is also not structured or organized, as it may not store or display all the necessary information about incidents.
Purchasing and deploying an incident management tool is not a good option, as it is not low cost or easy to implement within a week. It may require spending a significant amount of money and time on acquiring, installing and configuring the software or hardware.
Managing the incidents through emails and phone calls is not a good option, as it is not structured or organized. It may lead to confusion, inconsistency or loss of information about incidents. Verified Reference: A Study Guide to the ISTQB Foundation Level 2018 Syllabus - Springer, Chapter 3, page 32-33.

The following statements about risk-based testing are correct:
II) Tests should be prioritized to find tie critical detects as early as possible. Risk-based testing involves prioritizing tests based on risk level, which reflects both the likelihood and impact of defects or failures. Tests with higher risk level should be executed earlier than tests with lower risk level, in order to find and fix critical defects as soon as possible.
III) Non-testing activities may also help to reduce risk. Risk-based testing does not only involve testing activities, but also other activities that can help mitigate risks, such as reviews, inspections, audits, simulations or prototyping.

The correct set of data for valid equivalence class partitions should include one value from each equivalence class, and no value from outside the range. Option C satisfies this condition, as it has one value from each of the four equivalence classes (50, 100, 250, 500). Option A has two values from the same equivalence class (100 and 200), option B has values outside the range (0 and 0.99), and option D has two values from the same equivalence class (1000 and 500). Verified Reference: A Study Guide to the ISTQB Foundation Level 2018 Syllabus - Springer, page 35.

The extent of testing required for a software product depends on various factors, such as the level of risk, the budget, and the time available. The level of risk reflects the potential impact of failures on the stakeholders and the environment. The budget determines how much resources can be allocated for testing. The time available defines the schedule and deadlines for testing activities. The particular tester involved in testing is not a deciding factor for the extent of testing required, as testing should be based on objective criteria and not on personal preferences or abilities. Verified Reference: [A Study Guide to the ISTQB Foundation Level 2018 Syllabus - Springer], Chapter 2, page 14-15.

Independent testing is testing performed by a person or group that is independent of the development team. Independent testing can have various degrees of independence, ranging from testers who are part of the same organization as developers to testers who are external contractors or consultants. Independent testing can have various benefits, such as reducing bias, increasing objectivity, improving quality, or providing different perspectives. Independent testing is not necessary because developers don't know any testing, as this is a wrong and disrespectful statement. Developers can perform various types of testing, such as unit testing, component testing, or integration testing. However, independent testing can complement developer testing by providing additional levels of verification and validation, such as system testing, acceptance testing, or non-functional testing. Verified Reference: [A Study Guide to the ISTQB Foundation Level 2018 Syllabus - Springer], Chapter 2, page 16-17.