Concept:Vixen is the feminine term for a fox. The masculine counterpart is simply 'fox'.Explanation:A vixen specifically means a female fox. The male fox is also called a fox (the same word).Check the options:Ox is a male cattle (bullock), not related to vixen.Fox is the correct masculine for vixen.Horse is a different animal; its masculine is stallion.Deer is also different; its masculine is buck.Thus, only fox fits.Answer:The correct answer is option B: fox.