Which of the following is the masculine form of the given noun?Widow

The correct answer is Option (4) → Widower

A widow is a woman whose husband has died. A widower is a man whose wife has died.

Masculine	Feminine
(1) Husband: a married man	wife
(2) Nephew: the son of your brother or sister	niece
(3) Monk: a man who lives in a monastery and gives his life to religion	nun
(4) Widower (answer)	widow

Here the masculine is made from the feminine by adding -er: widow → widower.