KE depends on velocity. It is easier to answer this question in terms of the earth.
The closer the object (earth/comet) is to the sun, the faster it moves. that means that the fastest moving point would be as the comet/earth passes through point C.
The slowest speed would be the furthest away from the sun which is point A.
Answer: The faster the planet moves the greater the Kinetic Energy.
The Slower the planet moves, the less the KE.
Point A is where it is slowest with the lowest amount of energy.
Discussion
The formula for KE is KE = 1/2mv^2. The mass of the comet or earth is a constant. It doesn't change no matter which point the comet passes through. If v goes down KE will go down. If v goes up, KE goes up.