When may an airplane be dispatched if its airborne radar is inoperative and thunderstorms are forecasted?

The correct answer is that an airplane may be dispatched in day VFR conditions when its airborne radar is inoperative and thunderstorms are forecasted. This is because Visual Flight Rules (VFR) conditions allow pilots to navigate and control the airplane visually, which is particularly advantageous when flying in areas with thunderstorms. When flying in VFR, the pilot can maintain situational awareness and avoid hazardous weather, making it safer to operate the aircraft despite the radar being inoperative.

Operating under VFR conditions during the day means that the pilots have better visibility and can actively avoid thunderstorms and other weather hazards by following visual cues. This contrasts with conditions that might require additional instrument navigation or reliance on onboard radar systems.

Other options imply circumstances that may not be realistic or safe given the inoperative radar and the presence of thunderstorms. For instance, the ability to climb and descend VFR or dispatching under approved instrument conditions might not adequately address the safety risks associated with thunderstorms without operational radar guidance.