Which weight is defined as the maximum weight during taxi?

The maximum ramp weight is the correct choice because it represents the total weight of the aircraft when it is on the ground, prior to any fuel being consumed during taxi, take-off, or landing. This weight includes the aircraft's structure, passengers, cargo, fuel, and any other items onboard.

In the context of aircraft operations, the maximum ramp weight is crucial since it dictates the upper limit of what the aircraft can safely carry while stationary on the ground. Once the aircraft starts taxiing, it is at this weight that the aircraft must remain within regulatory and operational safety limits.

The other choices refer to different weight limits: the maximum zero fuel weight pertains to the total weight of the aircraft with all its payload but without usable fuel; the maximum take-off weight is the maximum weight at which the aircraft is allowed to attempt to take off; and the maximum landing weight indicates the maximum weight for a safe landing scenario. None of these specifically addresses the weight limit applicable during taxi operations.