Nouns identify names of people, places, animals, and things based on gender. Nouns can be classified into masculine, feminine, common, and neuter. Masculine nouns denote male members of species or male figures, Feminine nouns indicate female members of species or female figures, Common nouns are not gender-specific, and Neuter nouns point out items that lack gender. While “fox” is a gender-neutral noun, “tod” and “dog” are masculine, and “vixen” is feminine. So, the correct answer is “vixen.”