The correct answer is (a).
Section 376D of the Indian Penal Code, 1860, states that whoever, in committing rape, is in company with one or more other persons, shall be punished with rigorous imprisonment for a term which shall not be less than twenty years but which may be extended to life imprisonment.
The punishment for gang rape is more severe than the punishment for rape, which is rigorous imprisonment for a term which shall not be less than seven years but which may be extended to ten years. This is because gang rape is a more serious crime, as it involves multiple perpetrators who act together to commit the crime.
The punishment for gang rape is also more severe than the punishment for other forms of sexual assault, such as molestation and sexual harassment. This is because gang rape is a more violent crime, as it involves the use of force or the threat of force.
The punishment for gang rape is intended to deter people from committing this crime, and to protect victims of gang rape. The punishment is also intended to send a message that gang rape is a serious crime that will not be tolerated.