. Materials and Resources Credit, Building Product Disclosure and Optimization - Sourcing of Raw Materials, Option 2. Leadership Extraction Practices Natural rubber flooring is a bio-based material that can contribute to the achievement of Option 2 of the Sourcing of Raw Materials credit, which requires using products that meet at least one of the responsible extraction criteria for at least 25%, by cost, of the total value of permanently installed building products in the project1. By meeting the Sustainable Agriculture Standard (SAN), the natural rubber flooring demonstrates that it has been produced in a way that conserves biodiversity, protects natural resources, and enhances social and economic well-being2. Therefore, the cost of the substituted flooring ($80,000) can be counted towards the credit threshold.
Reference:
Reference Guide for Building Design and Construction v4 - Pages 263-2641 Sustainable Agriculture Standard | Rainforest Alliance3

Detailed
The Basis of Design (BOD) outlines the project design decisions and criteria, linking them to the Owner's Project Requirements (OPR). LEED requires this documentation to demonstrate alignment between the owner's goals and the building design, ensuring that sustainability objectives are met throughout the project lifecycle.

According to the LEED v4: Building Design + Construction Guide1, Option 2 of the Surrounding Density and Diverse Uses credit requires the project to be within walking distance of at least 10 diverse uses. The guide also states that "walking distance is defined as the distance that a pedestrian must travel between origins and destinations without obstruction, in a safe and comfortable environment on a continuous network of sidewalks, all weather-surface footpaths, crosswalks, or equivalent pedestrian facilities." Therefore, the documentation must include walking routes from the project to each use to demonstrate that the distance requirement is met. Reference:
LEED v4: Building Design + Construction Guide
CI-v4.1 LTc2: Surrounding density and diverse uses | LEEDuser

. Contractor
The contractor is the project team member who should be integrated early into the design phase to assist with earning the Materials and Resources Prerequisite, Construction and Demolition Waste Management Planning. The contractor is responsible for implementing the waste management plan, which includes estimating the types and quantities of waste materials, identifying the diversion strategies, selecting the waste haulers and recyclers, tracking and documenting the waste diversion performance, and training the subcontractors and workers. The contractor can provide valuable input on how to reduce, reuse, and recycle the construction and demolition waste, as well as identify potential challenges and opportunities for achieving the prerequisite requirements.
Reference:
Reference Guide for Building Design and Construction v4 - Pages 263-2641 LEED Certification and Sustainable Construction Waste Management1

The percentage of diverted waste for Materials and Resources Credit, Construction and Demolition Waste Management is calculated by dividing the total weight of diverted materials by the total weight of waste generated1. Diverted materials are those that are reused, recycled, salvaged, or donated2. In this case, the total weight of diverted materials is:
8 tons (7.3 tonnes) of recycled demolition steel and concrete
6 tons (5.4 tonnes) of used furniture donated to a non-profit organization
1 ton (0.9 tonnes) of removed carpet and ceiling tiles sent back to the manufacturer
40% of 3 tons (2.7 tonnes) of commingled scrap, which is 1.2 tons (1.1 tonnes) The sum of these weights is 16.2 tons (14.7 tonnes). The total weight of waste generated is 20 tons (18.1 tonnes). Therefore, the percentage of diverted waste is:
(16.2 / 20) x 100 = 81%
However, the credit allows for a 10% adjustment for vegetative waste, which is not considered a building material3. Therefore, the percentage of diverted waste after adjustment is:
(81 - 10) = 71%
The closest answer option to this value is B. 75%.
Reference:
Construction and Demolition Waste Management
Construction Waste Management
Construction and Demolition Waste Management - Canada Green Building Council