Which of the following is a masculine noun of the 1st declension?

In Latin, the first declension primarily includes feminine nouns that typically end in "-a" in the singular form. However, there is an exception with a few nouns that, although they belong to the first declension, are masculine. "Incola," which means "inhabitant," is one such noun. Despite its first declension endings, it refers to a male inhabitant when used in a specific context.

The other choices do not fit the criteria of a masculine noun in the first declension. "Puella" means "girl" and is a classic feminine noun. "Feminina" (meaning "feminine") is also feminine and is typically used similarly. "Familia," while used in everyday language to refer to a family, is predominantly a feminine noun in Latin as well. Thus, "Incola" stands out as the only masculine noun among these options, making it the correct answer.