Define Acceleration.
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Acceleration is the name we give to any process where the velocity changes. Since velocity is a speed and a direction, there are only two ways for you to accelerate: change your speed or change your direction—or change both.

Acceleration is the rate of change of velocity per unit of time.Usually, acceleration means the speed is changing, but not always. When an object moves in a circular path at a constant speed, it is still accelerating, because the direction of its velocity is changing.

Explanation:

It is given that comet A has higher eccentricity than comet B and according to Kepler law planet orbit around the sun with the sun as the focus.

An implication of Kepler's law is that the planet moves faster when it close to the sun and slower when distant. This is the result of the conservation of angular momentum.

A has a more elliptical path thus it will be closer to the sun and therefore A will have the highest orbital speed.