An insulating plastic rod is charged by rubbing it with a wool cloth, and then brought to an initially neutral conducting metallic sphere sitting on an insulating stand. The rod touches the sphere for a few seconds, and then is separated from the sphere by a small distance. After the rod is separated, the rod:
A) is repelled by the sphere.
B) is attracted to the sphere.
C) feels no force due to the sphere.

A) is repelled by the sphere.

Explanation:

When a charged insulated rod is touched with an insulated conducting sphere , some  charge on the rod gets transferred to the sphere . So they become similarly charged . We all know that there is repulsion when two similarly charged object are brought near to each other . Hence here too there will be repulsion between the rod and the sphere when the rod is brought near the sphere.

radiation

explanation:

heat is transmitted by radiation