1. at the very top of the track, what type of energy is greatest?

Brief Explanations:

At the top - most point of a track, an object has maximum height relative to the lowest point of the track. Gravitational potential energy is given by $U = mgh$ (where $m$ is mass, $g$ is acceleration due to gravity and $h$ is height). As height $h$ is maximum at the top, gravitational potential energy is the greatest.

Answer:

Gravitational potential energy