When Building Soap Box Cars Which Race by Coasting Downhill

When building soap box cars which race by coasting downhill it is better to have solid wheels rather than ones of equal mass with spokes because

A) The solid wheels have a lower moment of inertia and therefore accelerate faster.
B) The solid wheels are easier to paint.
C) The solid wheels have a higher moment of inertia and therefore retain more rotational energy.
D) The wheels with spokes lose too much energy by heating up the air.