In which airspace can you operate without a specific altitude?

Operating in Class G airspace does not require a specific altitude, which is why this is the correct answer. Class G represents uncontrolled airspace where pilots have the freedom to operate without specific altitude restrictions. This type of airspace allows pilots to fly according to visual flight rules (VFR) without the need for air traffic control clearance or adherence to specific altitude assignments, providing flexibility especially in less congested areas.

In contrast, Class A airspace is designed for IFR (Instrument Flight Rules) operations and requires pilots to maintain specific altitudes, generally above 18,000 feet ASL where air traffic control is actively managing traffic. Class E airspace, which is generally used for transitioning between controlled and uncontrolled airspace, can also have altitude restrictions depending on its configuration. Class D airspace surrounds airports with operational control towers, where specific altitudes and communication with air traffic control are mandated for safety and efficiency in managing nearby traffic.