Which type of airspace is not allowed for visual flight rules?

Visual Flight Rules (VFR) require pilots to operate under certain weather conditions and have specific airspace requirements they must adhere to. Class B airspace is the only type of airspace listed that has strict operating requirements, including the need for communication with air traffic control and typically a higher level of separation from other traffic.

In Class B airspace, the pilot must have a specific clearance to enter, and VFR operations are often limited, particularly in terms of altitude, to ensure safe separation from the high volume of air traffic operating under Instrument Flight Rules (IFR). The design of Class B airspace is to protect high-density terminal areas of air traffic and may not allow VFR flights at all times, especially during peak traffic periods.

In contrast, Class C, D, and E airspaces allow for VFR operations, although they may have certain requirements such as communication with air traffic control or weather minimums. Each of these classes has different complexities and traffic levels, but they do not impose the same strict operating restrictions as Class B airspace. Therefore, Class B is the correct choice as it serves to ensure safe separation in high-traffic environments, making VFR in this airspace typically restricted or subject to specific ATC clearance.