A site survey is the formal assessment used to determine the optimal number and placement of wireless access points (APs). According to Security+ SY0-701, wireless site surveys evaluate factors such as building layout, RF interference, wall material density, antenna propagation, and signal overlap. The goal is to ensure full wireless coverage while minimizing the number of APs needed, maximizing performance, and reducing dead zones.

During a site survey, technicians analyze:

Signal strength patterns

Interference sources (microwaves, metal shelving, wiring, etc.)

Required coverage zones

Capacity needs (number of users, devices)

Although heat maps (C) visually represent wireless signal distribution, they are a result of a site survey, not the process itself. WPA3 (B) is a security protocol unrelated to determining coverage. A signal locator (A) is not an enterprise-grade planning tool.

Therefore, the correct answer is D: Site survey.