Which option describes the greatest common factor?

The greatest common factor (GCF) refers to the largest number that can perfectly divide two or more numbers, meaning that it is a common factor among those numbers. The GCF is especially useful in simplifying fractions or finding common denominators. When identifying the GCF, you look for the factors of each number and choose the largest one that appears in all sets of factors.

In this case, choice C accurately defines the GCF by stating it is the largest factor that two or more numbers have in common. This highlights its primary purpose in relation to multiples and divisibility, reinforcing the concept that the GCF helps in understanding the shared characteristics of the involved numbers.