A heart beats 264 beats in 3 minutes. What is the unit rate?

To find the unit rate, we divide the total number of beats by the total time.

In this case, there are 264 beats in 3 minutes.

So, the unit rate is 264 beats / 3 minutes.

Simplifying this rate, we get 88 beats per 1 minute.

Therefore, the correct answer is C - 88 beats in 1 minute.