Which of the Following Statements Is True

Which of the following statements is true?

A) Bore is the correct term to apply to the radius of the interior of a weapon's barrel.
B) In a rifled bore, the bore is measured from one groove to an opposing groove.
C) With a rifled bore, the projectile usually rotates in a left-hand direction.
D) It is possible to fire a smaller caliber bullet through a larger bored weapon.