The Correct Formula for Effect Size Using Cohen's D for a Paired-Samples

Multiple Choice

The correct formula for effect size using Cohen's d for a paired-samples t test is:

A) (M - $\mu$ ) /s + $\sigma$ .
B) (M - $\mu$ ) /s.
C) (X - $\mu$ ) /s.
D) ( $\sigma$ - $\mu$ ) /s.