What equipment is required for aircraft operating in Class B airspace?

For aircraft operating in Class B airspace, the requirement is to have two-way radio communication capabilities with Air Traffic Control (ATC) and a Mode C transponder. This requirement is put in place to ensure that ATC can communicate effectively with aircraft operating within the busy airspace around major airports, where maintaining safe separation from multiple aircraft is critical.

Two-way radio communication allows pilots to receive instructions from ATC and respond, which is essential for the coordination required in Class B airspace. The Mode C transponder provides altitude information along with the aircraft's identification to ATC, enhancing their ability to monitor and manage traffic. This dual equipment requirement is vital for maintaining safety in an area that typically experiences high traffic density.

The other options do not meet the standards set for operating in Class B airspace. For instance, one-way communication or basic VFR equipment alone would not provide the necessary interaction or data needed for safety in this airspace environment.