What is the square root of 64?

The square root of a number is a value that, when multiplied by itself, results in the original number. For example, the square root of 64 can be determined by finding a number that, when squared, gives you 64.

In this case, 8 multiplied by 8 equals 64 (8 × 8 = 64). Therefore, the square root of 64 is indeed 8. This demonstrates that C is the correct choice, as it accurately identifies the number that, when squared, results in the original number of 64.

The other choices do not yield 64 when squared. For instance, 6 squared equals 36, 7 squared equals 49, and 9 squared equals 81. Thus, they are not the correct answers.