Homer Sharpens a Rock and Uses It to Shave

Homer sharpens a rock and uses it to shave.Schick adds a handle to the rock for better grip.Gillette then changes the rock to a titanium blade for durability.The progression of improvements made to the shaving utensil is an example of

A) cultural adaptation.
B) emulative learning.
C) eureka effect.
D) cultural bootstrapping.
E) ratchet effect.