The LEED for Neighborhood Development rating system has four certification levels: Certified, Silver, Gold, and Platinum. Each level requires a minimum number of points to achieve, based on the total number of available points in the rating system. The total number of available points is 110, and the minimum points for Platinum certification is 801. Therefore, the maximum points a new construction platinum LEED for Neighborhood Development certification level can earn are 110 - 80 = 30 points. However, there are also four regional priority credits that can be earned for addressing geographically specific environmental issues2. These credits are worth one point each, and can be added to the total score of a project. Therefore, the maximum possible points a new construction platinum LEED for Neighborhood Development certification level can earn are 30 + 4 = 34 points. However, the question asks for the maximum points that can be earned by a new construction project. According to the LEED Reference Guide for ND, new construction projects must meet all prerequisites and achieve at least 50% of the points available under the Green Infrastructure and Buildings category3. This category has 21 criteria, each worth one point, except for Certified Green Buildings, which is worth up to five points4. Therefore, the maximum points available under this category are 21 + 4 = 25 points. Since new construction projects must achieve at least 50% of these points, they must earn at least 13 points under this category. This means that they have less points to earn under the other categories (Smart Location and Linkage, and Neighborhood Pattern and Design), which have a total of 32 criteria worth one point each4. Therefore, the maximum points a new construction project can earn under these categories are 110 - 25 - 13 = 72 points. Adding the regional priority credits, the maximum possible points a new construction project can earn are 72 + 4 = 76 points. To achieve Platinum certification, a new construction project must earn at least 80 points1. Therefore, the maximum points a new construction platinum LEED for Neighborhood Development certification level can earn are 80 - 76 = 4 points under each of the four categories: Smart Location and Linkage, Neighborhood Pattern and Design, Green Infrastructure and Buildings, and Regional Priority Credits. Hence, the answer is D. 16.
Reference:
LEED certification for neighborhood development
LEED Reference Guide for ND
LEED for Neighborhood Development - Wikipedia
LEED rating system
LEED for Neighborhood Development - Infrastructure Tool Navigator

Occupant surveys are tools that can be used to identify indoor environmental issues and prepare a corrective action plan to make necessary changes. Occupant surveys are questionnaires that collect feedback from the building users about their satisfaction, comfort, health, and productivity in relation to the indoor environmental quality (IEQ) factors, such as thermal comfort, indoor air quality, lighting quality, acoustic quality, and occupant control. Occupant surveys can help to identify the sources and causes of IEQ problems, as well as the potential solutions and improvements. Occupant surveys are also required for some LEED credits, such as IEQc7.2 Thermal Comfort, Verification1, which requires a corrective action plan if more than
20% of the occupants are dissatisfied with the thermal conditions in the space2. The other options are not directly related to identifying indoor environmental issues and preparing a corrective action plan, as they involve different types of tools or metrics that are not relevant for measuring occupant satisfaction and comfort.

Explanation
Water Efficiency is the only credit category that does not have a prerequisite in LEED v4 for Building Design and Construction. Prerequisites are the minimum requirements that all projects must meet to be eligible for LEED certification. They are mandatory and non-weighted, meaning they do not contribute to the project's score. The other credit categories have at least one prerequisite each, as shown in the table below:

References: LEED v4 Reference Guide for Building Design and Construction, p. 17 1; [LEED v4 BD+C Scorecard]

Graywater refers to relatively clean wastewater from domestic activities such as washing dishes, laundry, and bathing. Water from lavatory faucets falls into this category. Graywater can be treated and reused for non- potable purposes such as toilet flushing or irrigation, which can help conserve water. References: LEED Green Associate Candidate Handbook, U.S. Green Building Council resources