In Which One of the Following Situations Is Linear Momentum

In which one of the following situations is linear momentum not conserved?

A) A bomb suspended by a string explodes into one hundred fragments.
B) A bowling ball collides with a set of ten pins.
C) A golf ball is struck by a club.
D) An astronaut floating in space throws a hammer away and subsequently moves in the opposite direction.
E) A tree limb is struck by lightning and falls to the ground.