Which of the following is a correct pair of masculine and feminine gender?

Cock:Hen

The correct pair of masculine and feminine gender is Cock:Hen.

• Boar:Boaress is not a correct pair because boaress is not a commonly used word.
• Viceroy:Viceroy is not a correct pair because both words are masculine.
• Chairman:Chairwomen is not a correct pair because the feminine form of chairman is chairwoman.

The feminine form of cock is hen. A hen is a female chicken, while a cock is a male chicken. So, the pair cock:hen is a correct pair of masculine and feminine gender.