Question

the prefix semi- means halfway or partway. something that is semiannual occurs a year, or twice a year.
what is a \semicircle\?
a half a circle
b one full circle
c something that is not a circle
d too many circles

Explanation:

The prefix "semi-" means halfway or partway. So, combining "semi-" with "circle", a semicircle should be half of a circle. Option A matches this meaning, while B (full circle) is incorrect, C (not a circle) is wrong, and D (too many circles) is also incorrect.

Answer:

A. half a circle