Topic: Gender (লিঙ্গ),

Best Answer Explained in Below-:

The question asks for an example of a masculine gender among the provided options. To clarify, gender in biological terms often refers to the sex of animals, and it is categorized into masculine (male), feminine (female), and sometimes neuter.

1. **Vixen (A)**: This term refers specifically to a female fox, thus it is feminine.

2. **Doe (B)**: A doe is a female deer, rabbit, or similar animals, signifying another feminine gender.

3. **Roe (C)**: The term "roe" typically refers to the eggs of fish, particularly salmon and trout, but when used to describe an animal, it often refers to the female deer in the context of "roe deer." This is also feminine.

4. **Stag (D)**: A stag is an adult male deer, especially of species such as red deer and elk. This makes it a clear example of masculine gender.

Thus, among the given options, "stag" stands out as the only term denoting a male counterpart, making **D: stag** the correct answer. Understanding these distinctions can help in recognizing gender classifications in zoology and related discussions.