Answer:
The correct answer is "altos and sopranos"
Step-by-step explanation:
The plural form of the nouns alto and soprano are formed by just adding an "s".
The word "alto" means a type of voice within a choir.
The word "soprano" means someone (men, women, girl or boy) with the highest voice in a choir.
The rest of the options, altoes and sopranoes, are incorrect since the plural form is by just adding the "s".