One who sacrifices his life for a cause

A. Patriot

B. Martyr

C. Revolutionary

D. Soldier

Answer: Option B

Solution(By Examveda Team)

One word substitute is Martyr.

Patriot: a person who vigorously supports their country and is prepared to defend it against enemies or detractors.
Martyr: a person who sacrifices his life for a cause.
Revolutionary: engaged in or promoting political revolution.
Soldier: a person who serves in an army.