Question

most warning signs are
a diamond-shaped.
b oval-shaped.
c square-shaped.
d round-shaped.

Explanation:

In traffic safety, most warning signs (like those indicating hazards) are diamond - shaped. Oval - shaped signs are usually for railroad warnings, square - shaped are often regulatory or informational, and round - shaped are typically regulatory (like stop signs are octagonal, but round is for some other regulatory, while warning is diamond - shaped). So the correct option is A.

Answer:

A. diamond - shaped.