Step-by-step explanation
Let's assume that we have a circle of radius r. Its circumference or perimeter C and its surface area A are given by the following formulas:
We must find the radius or diameter of a circle where C and A are equal. Then we can construct an equation for r by equalizing A and C:
We can divide both sides by π and r (it is important to note that we can divide by r because we know that r is not 0). Then we get:
Answer
So the radius is 2 (of any unit). Then the answer is the first option.