The shape of a sign warns you of what is ahead.
a. true
b. false

True

Explanation:

Hi, is true but it is also the color. The shape of a sign is to warn people that are colored blind and can't see the "red" stop sign. So they know is a stop sign because of the 8 sides on it, or a warning sign because of the diamond shape.

Also the symbol on the sign is important, for example: the STOP word in the stop sign.

answer; collective security;

quote is the answer your looking for.