In a Meta-Analysis by Spence Et Al (2005) It Was

In a meta-analysis by Spence et al (2005) it was reported that there is a small, significant, positive effect of physical activity on global self-esteem in adults. However, this effect was moderated by what?

A) A significant change in fitness
B) Baseline levels of fitness
C) The program design variables including exercise frequency, intensity, or duration
D) Baseline level of self-esteem