Correct answer for Miguel necesitaba unos medicamentos y compró ________ en la farmacia?

Hola Ramesh P.

You are correct to question this. In that sentence, the noun medicamentos is plural, so when it is replaced by a pronoun, the correct form is:

Here, algunos means "some (of them)" and replaces the plural noun medicamentos.

Using alguno would be singular ("one" or "some one"), so it would not agree with the plural noun being replaced.

If the exercise was asking you to replace medicamentos, then algunos is the correct answer. If an AI assistant suggested alguno, that would be an error.

I hope that clears things up!

Silvia