The muffins were fresh. When discussing tenses, the subject of the previous sentencesthe can be called the

1. first person plural
2. second person plural
3. third person plural
My answer 1. first person plural

This doesn't make sense. Are some words missing or something?

The subject (muffins) is certainly plural, but it's not first person.

1st: I,we
2nd: you
3rd, he,she,it,they

Given that, what does it have to do with tenses?

Well, I guess it does in this case. As far as I recall, the verb "to be" is the only one where the past tense differs between singular and plural. Person still doesn't matter.

Third person plural. " the muffins are fresh. THEY(3rd person plural) were made an hour ago."

Actually, the correct answer is 3. third person plural. When discussing tenses, the subject of the previous sentence is referred to as the third person plural because it refers to a group of people or things other than the speaker(s) or the person(s) being spoken to. In this case, "the muffins" are the subject, and they are considered as a third person plural entity.