C.
Although this is not the exact answer the circumference formula is 2(pi)r. Which is far more than the other two options.
Answer:
8
Step-by-step explanation:

× 8
= 3
In algebra:
× y = 3
y = 3 ÷ 
y = 8
#1
That is false..one could have side lengths of 9 and 1, and the other could have side lengths of 3. Both the areas would be 9, but the figures would not be congruent.
#2
That is true, they must both have the same side length to have the same perimeter, therefore they will also have the same area.