Which measure of central tendency refers to the value that appears most frequently in a data set?

The other answer is correct, but doesn't give the answer needed, so continuing with that:

Median - Separates data sample, "middle" value.

Mode - The value that appears most often.

Mode is a measure of central tendency that refers to the value that appears most frequently in a data set.

For anyone still looking for the answer = )

(This answer was copied/pasted from another question, which I also answered.)

Median and Mode;

The only measures of central tendency that can be used for ordinal data.

Values are ranked relative to each other but are not measured absolutely.