Geometry

Question Analysis:
This conceptual question tests properties of pyramids instead of visual recognition.
The main focus is on structural requirements of pyramid surfaces.

Key Concept Explanation:
A pyramid has flat, triangular lateral faces — no curved surfaces.
A curved side surface belongs to a cone.

Step-by-Step Solution:
A: Valid feature of a pyramid
B: True — only one base
C: Curved side → invalid
D: ...