Why is it necessary to inform the receiving controller of traffic observed?

Informing the receiving controller of the traffic observed is essential to confirm that aircraft are effectively integrated into the airspace management system. This communication allows the receiving controller to maintain situational awareness and manage traffic efficiently. By sharing information about observed traffic, the receiving controller can make informed decisions about spacing, altitude changes, or any other necessary adjustments to maintain safety and efficiency in the airspace. This practice is crucial in ensuring that all aircraft are accounted for and that the operations of the airspace are smooth, minimizing the risk of collisions and other hazards.

The other options deal with different aspects of air traffic control but do not directly capture the primary purpose of notifying the receiving controller about observed traffic. Option A relates more to route planning than to the immediate management of traffic integration. Option C pertains specifically to go-around procedures, which may be a separate consideration. Option D addresses regulatory compliance, which is certainly important, but the primary focus here is on the operational need for traffic coordination and safety management.