The correct option is A. Gay marriage.
Gay marriage is the marriage between two people of the gender or sex. The couple enters into in a religious or civil ceremony. At the beginning of the 21st century, marriage with the same sex has been legalized. The supporters of gay marriage belief that any ban or restriction on gay marriages is unconstitutional and discriminatory. They also claim that the same-sex couples should also enjoy all the benefits that are enjoyed by different-sex couples.