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# Circle Circumference

ACTMAT-GKENY3

Blowing air into a spherical ball caused the circumference of the ball to increase from 12 inches to 16 inches.

By how many inches, then, did the radius increase?

A

$4$

B

$2$

C

${\cfrac { 2 }{ \pi } }​$

D

$\cfrac{4}{\pi}$

E

$2{\pi}$