Answer: (c) when the plane makes a narrow angle with the base.
Step-by-step explanation: The prism has a base which is a 9 sided polygon. If the intersecting plane is parallel to the base, then the intersection is either null or the base itself. So, option (a) is incorrect. Options (b) is also not correct because in that case also, the intersection is a polygon having number of sides less than 10 (see attached fig.). The only remaining and correct answer is (c).
Thus, the correct option is (c).
