Which of the following can be an indication of a landing gear malfunction?

An unusual noise during landing is indeed a significant indication of a landing gear malfunction. When the landing gear is deployed, it should operate quietly and smoothly. Any strange sounds—such as grinding, clunking, or unexpected mechanical noises—could suggest problems with the gear's mechanisms, such as failed components, misalignment, or foreign objects obstructing the gear. These noises could indicate that the gear is not fully extended or locked, which poses a risk during landing and can lead to severe consequences if not addressed.

In contrast, options like true level flight, low fuel levels, and steady airspeed do not directly indicate a landing gear issue. True level flight can be achieved even if the landing gear is malfunctioning, and low fuel levels relate more to fuel management rather than mechanical issues with the gear. Steady airspeed during descent is also a normal operational parameter and does not reflect any specific condition of the landing gear. Therefore, the occurrence of unusual noises during landing serves as a critical signal of potential failure or malfunction in the landing gear system that pilots should be attuned to.