ANSWER
30 in.
EXPLANATION
The formula for calculating the circumference of a circle in terms of diameter is
[tex]C = \pi \: d[/tex]
It was given to us that the circumference is C=30π in.
We substitute this into the formula to obtain;
[tex]30\pi= \pi \: d[/tex]
Divide both sides by π to get,
[tex]30 = d[/tex]
The diameter is 30 in.
The second choice is correct.
