Question

bullets spin when shot from a rifle or handgun. what causes this spinning?
a primer
b action
c cartridge
d rifling

Explanation:

Rifling refers to the spiral grooves inside a gun barrel. When a bullet is fired, these grooves cause the bullet to spin. This spinning motion (like a gyroscope) stabilizes the bullet in flight, improving accuracy. A primer (A) is a small explosive charge in a cartridge that ignites the gunpowder. The action (B) is the mechanism of the gun that loads, fires, and ejects cartridges. A cartridge (C) is the ammunition unit that contains the bullet, gunpowder, and primer. None of these (A, B, C) directly cause the bullet's spinning. Only rifling (D) creates the spiral - forcing contact that imparts spin to the bullet.

Answer:

D. rifling