The answer is B
A. 6(a+5)
=6a+30 not equivalent to 6a+15
B.3(2a+5)
=6a+15 is equivalent
C.3(3a+12)
=9a+36 not equivalent
D.6(a+12)
=6a+72 not equivalent
So your answer is B
I believe the answer is the second one I am in the same class.
First, find the relationship of the circumference to its diameter by finding that the length of the diameter wraps around the length of the circumference approximately π times. Use this relationship to writing an equation showing the ratio of circumference to diameter equaling π. Then rearrange the equation to solve for the circumference. Substitute the diameter for 2 times the radius