Final answer:
The base shape of a cylinder is a circle.
Step-by-step explanation:
A cylinder is a three-dimensional shape that has two congruent circular bases and a curved surface connecting the two bases. The base shape of a cylinder is a circle (option C). Bases are the flat, bottom surfaces of a solid shape, so the base shape is what the solid shape would sit on if it were placed on a flat surface.
For example, if you have a drinking glass, the bottom of the glass is a circle, which is the shape of the base of a cylinder.
Therefore, the correct answer is option C) circle.