Like whats the answer a b c or d

The circumference of a circle is 5 pi cm. what is the area of the circle?

What is the length of the unknown leg in the right triangle ?

Which approach to the theory-and-research cycle does the following sequence reflect: (1) specific observations suggest generalizations, (2) generalizations produce a tentative theory, (3) the theory is tested through the formation of hypotheses, and (4) hypotheses may provide suggestions for additional observations?