For several years, advertisements for Arm & Hammer baking soda have prompted consumers to place an opened box of the product in the refrigerator to lessen food odor and to replace that box monthly. The same ads advise customers to pour the used box down their kitchen sinks to freshen drains. Arm & Hammer employed a __________ strategy in its attempt to sell more baking soda.
a) Market penetration
b) Market development
c) Product development
d) Diversification
e) Product penetration