Question

most axons of the dorsolateral corticorubrospinal tract synapse on

interneurons of the spinal gray matter that in turn synapse on motor neurons that project to the distal muscles of the arms and legs.
motor neurons that project to the fingers.
betz cells.
muscles of the fingers and thumb.

Explanation:

The dorsolateral corticorubrospinal tract axons mainly synapse on interneurons of the spinal gray matter. These interneurons then synapse on motor neurons projecting to distal muscles of the arms and legs. This pathway is important for fine - motor control of distal limb muscles.

Answer:

interneurons of the spinal gray matter that in turn synapse on motor neurons that project to the distal muscles of the arms and legs.