The term hit wicket in cricket refers to

when the bowler bowls out three batsman with three successive balls
when the batsman intercepts the ball with his leg or any part of his body between the wicket
when the batsman, while hitting the ball, strikes his own wicket with his bat or body and is declared out
None of the above

The correct answer is C.

A hit wicket is a dismissal in cricket when the batsman, while hitting the ball, strikes his own wicket with his bat or body and is declared out. The batsman is considered to be out even if the ball does not touch the wicket, as long as it is clear that he was trying to hit the ball.

Option A is incorrect because it describes a hat-trick, which is when a bowler dismisses three batsmen in three consecutive deliveries.

Option B is incorrect because it describes a leg bye, which is when the batsman hits the ball with his leg and it runs away to the boundary without being touched by a fielder.

Option D is incorrect because it is not a valid option.