Lenny cannot reach the bathroom shelf where his father keeps the electric toothbrush, but he ...

Lenny cannot reach the bathroom shelf where his father keeps the electric toothbrush, but he continues trying, day after day. After seeing his brother use a stool to open the kitchen cupboards, Lenny pushes the stool into the bathroom and uses it to finally get the toothbrush. How would Lenny's behavior be classified by learning theorists?
 
  a. Lenny's new behavior is the result of maturation, not learning.
  b. Lenny has learned how to reach the bathroom shelf through associative learning.
  c. Lenny has learned to compare his own physical growth with highplaces.
  d. Lenny was classically conditioned to use stools to extend his reach.