Capacity refers to:

• A. Ability to handle a given volume of traffic
• B. Number of runways
• C. Quality of weather data
• D. Aircraft performance

Answer: (A)

Capacity is about how much traffic the system can handle in a given period. In aviation terms, it refers to the maximum throughput the airspace, airport, or air traffic management system can manage safely and efficiently under current conditions. That’s why this option is the best definition: it captures the idea of throughput potential and limitations of the overall system, not just a single asset or piece of data. The other ideas don’t fit as the definition of capacity: the number of runways is a resource that can influence capacity but isn’t capacity itself; the quality of weather data is about information reliability, not how much traffic can be processed; and aircraft performance relates to what an individual plane can do, not the system’s ability to handle traffic.