He climbed up a stationary wagon.

moving
speeding
shunting
standing

The correct answer is D. standing.

A wagon is a vehicle

with low sides and no roof, typically drawn by horses or oxen. It can be used to transport goods or people. A stationary wagon is a wagon that is not moving. It is standing still.

The other options are incorrect because they describe wagons that are moving. A moving wagon is a wagon that is in motion. A speeding wagon is a wagon that is moving very fast. A shunting wagon is a wagon that is being moved around in a railway yard.