(i think the answer is a, am i right? ) most regulatory signs are a. octagonal and red or white b. circular and blue or green c. rectangular and red or white d. rectangular and yellow

Explanation:

In the United States, roadway sings use symbols to communicate specific aspect to drivers in the minor time possible. These sings can have different shapes and colors. They can be used to warn, guide, regulate, to remark school zones, even zones where there are constructions in process.

In the specific case of regulatory signs, they are octagonal shaped, and their color is often red, sometimes white. The best example of a regulatory sing is Stop signs, which are red and octagonal. It's important to say that not all regulatory signs are octagonal, but the vast majority of them are red or white.

So, what's the most common shape of regulatory signs?

Most of them are rectangular, the image attached shows regulatory signs in the United States, there you'll see that most of then are rectangular.

Therefore, the right answer is C.