Answer:
"Eduardo did not use the correct formula for the circumference"
Explanation:
The circumference formula is C = 2πr
Area formula is A=πr^2
Volume formula is correct. The steps area also correct to find r, the radius.
But in the end, he put the formula for circumference wrong. He used the formula for Area, NOT Circumference.
Hence, "Eduardo did not use the correct formula for the circumference" should be the correct choice for this question.