The correct answer is D. Document total waste per building floor area.
According to the LEED v4.1 Reference Guide for Building Design and Construction, Option 2 of the Construction and Demolition Waste Management credit requires projects to reduce the total construction waste generated by the project to less than 12.2 kilograms per square meter (2.5 pounds per square foot) of the building's floor area1. This option rewards projects for implementing waste prevention strategies, such as designing for material optimization, prefabrication, modular construction, deconstruction, and reuse1. To meet the requirements of this option, projects must document the total weight or volume of all construction waste generated by the project, excluding land-clearing debris and excavated soil, and divide it by the building's floor area1. Projects must also provide a narrative describing the waste prevention measures taken during design and construction1.

Source reduction focuses on minimizing waste at its origin.
* Prefabrication reduces waste by manufacturing components off-site with optimized material use, leading to less on-site cutting, packaging waste, and construction debris.
* Custom design (Option A) and design-build (Option B) do not inherently reduce waste.
* Material science (Option C) refers to material properties but does not directly address waste reduction.
Prefabrication is the most effective source reduction strategy, making Option D correct.
(Source: Official LEED BD+C Reference Manual)

The bonus location valuation factor in several Materials and Resources credits under LEED AP BD+C V4 is intended to incentivize the purchase of products that support the local economy. Products extracted, manufactured, and produced within 100 miles (161 km) of the project are valued at 200% of their cost within the calculations1. This adds value to locally produced products and materials2.

LEED project boundaries that include multiple similar buildings which are all eligible for certification can be registered as a group project. A group project allows multiple buildings (or interior spaces within multiple buildings) on a shared site to be certified as a single LEED project. These projects must meet the criteria outlined in the LEED Campus Guidance for Projects on a Shared Site, such as having the same construction contract, ownership, management, space type, rating system, and compliance paths. A group project will receive one certification and rating for the entire group.References: Group Projects (previously Multiple Building Projects), CAGBC News, September 1, 2020.

The Solar Reflectance Index (SRI) is a measure of the roof's ability to reject solar heat, as shown by a small temperature rise. It is defined so that a standard black (reflectance 0.05, emittance 0.90) is 0 and a standard white (reflectance 0.80, emittance 0.90) is 100. SRI is calculated using the roof surface's Solar Reflectance (SR) and Thermal Emittance (TE). SR is the fraction of solar energy that is reflected by the roof, and TE is the relative ability of the roof surface to radiate heat. Therefore, SRI includes the measure of a material's ability to reflect solar radiation, but not its ability to absorb or emit thermal radiation.
References:
* What is the Solar Reflectance Index? - Cool Roof Rating Council
* Definitions and Terms | HEATISLAND