The answer I believe is b
Hi there!
First we need to remember the following.

Now substitute both of the formulas.

Work out the parenthesis.

And finally collect terms.

~ Hope this helps you!
I’m pretty sure the answer is (2,1)
Answer:
pi x diameter
Step-by-step explanation:
To find the circumference of any given circle, multiply the radius by 2 to get the diameter, and then the diameter by pi (3.14)