Which of the following is NOT a requirement for operating in Class B airspace?

Operating in Class B airspace requires specific regulations to ensure the safety and organization of air traffic. Among these, two-way radio communication is essential, as pilots must establish and maintain communication with air traffic control (ATC) to receive instructions and clearances when operating in this highly congested airspace. An altitude-encoding transponder is also required; this equipment helps ATC monitor air traffic effectively by providing altitude data along with the aircraft's position.

Additionally, student pilots are required to have an endorsement from their instructor, confirming their training and proficiency to operate in Class B airspace. This endorsement ensures that even student pilots are adequately prepared to handle the complexities of flying in this environment.

Visual flight rules (VFR) clearance, while often necessary for VFR flights, is not a distinct requirement for operating in Class B airspace as it is not explicitly defined in the regulations. Pilots typically fly under VFR in Class B airspace, but they must comply with ATC instructions once communication has been established rather than specifically needing a VFR clearance. Therefore, while understanding VFR is crucial, "clearance" in this context is not a formal requirement for operating in Class B airspace, making it the correct answer.