Answer:
C. Voting for the US president.
Step-by-step explanation:
A revolution is any sharp or strong change that may be political, geographical, or even economical, but mostly revolutions are political. In simple words, revolutions are when people protest and demand reformation or bring about a significant change to an already existing system.
In the given options, the voting of the US president is not a revolution but rather a democratic decision to choose or elect a leader for the country. It is a change, but not a string or rebellious change that people pressed or revolt about.
Thus, the correct answer is option C.