What is the purpose of 'holding fuel' in a fuel plan?

The purpose of 'holding fuel' in a fuel plan is to have a reserve of fuel available for situations that could lead to delays, such as weather changes, extended holding patterns, or other unforeseen circumstances that may prevent an immediate landing at the planned destination. This ensures that the pilot can maintain a safe operating environment and have the flexibility to respond to changing conditions without risk of fuel exhaustion. Carrying extra fuel for holding allows pilots to adapt to delays while still ensuring they can reach their intended destination safely, or divert to an alternate if necessary.

The other choices, while related to fuel calculations, are focused on specific scenarios like taxiing or landing at the destination rather than contingency planning for unexpected events, which is the primary function of holding fuel.