The area of a circle is calculated as pi*(r^2). Given a diameter of 26 cm, the radius is half the diameter, which is 26/2 = 13 cm.
Therefore the area is pi*(13^2) = 169 pi.
Another alternative formula for the area is pi*(d^2 / 4). Substituting d = 26 would give pi*(26^2 / 4) = pi*(676/4) = 169 pi, which is the same answer.
So the correct answer is C.