There are 12 ducks and 15 geese swimming in a pond. What is the ratio of geese to total birds at the pond?

A. 12:27
B. 27:12
C. 15:27
D. 27:15

The total number of birds is 12 + 15 = 27. The ratio of geese to total birds is 15:27. Therefore, the answer is C. 15:27.