The figure below is a dartboard consisting of four concentric circles. This board is divided into four parts, labeled A, B, C, and D (where region A is a circle, and regions B, C, and D are rings). The radius of the inner circle is 1 cm, as is the distance between the subsequent rings.

What is the probability that a dart thrown at the dartboard lands in ring C? Assume the dart hits the board, and the dart lands in region A, B, C, or D (the thickness of each circle is negligible).