Answer:
Hi!
The answer to this would be option <u>A, Stereos</u>.
Explanation:
<u>Echo and mosquito</u> are words that require their ending to be changed to "<em>es</em>" in order to be converted from singular to plural. So the plural of echo and mosquito would be <u>echo</u><u>es</u> and <u>mosquito</u><u>es</u>.
In the case of <u>shampoo</u>, the rule is different and the word needs just a letter "<em>s</em>" at the end to become plural. Therefore, the plural of shampoo would be <u>shampoo</u><u>s</u> (speaking in reference to various types or a collection of shampoos).
Just like "shampoo", "stereo" also needs a letter <em>s</em> at the end of the word to become plural. Therefore, the word <em>stereos</em> is correct.