When All Behaviors Can Occur Freely,a Child Spends 30 Minutes

When all behaviors can occur freely,a child spends 30 minutes playing with blocks,15 minutes playing with crayons,and 5 minutes playing with a truck.Premack's principle predicts that

A) playing with blocks will reinforce playing with crayons
B) playing with crayons will reinforce playing with the truck
C) both a and b
D) neither a nor b