Perry applies a small amount of liquid between his dog's shoulder blades each month. The liquid helps prevent insects from bothering his dog. Lately, the liquid does not keep fleas off his dog. What is the likely change?
A. The fleas that survived exposure to the liquid have produced offspring that are resistant to the liquid.
B. The weather conditions have changed. There are more fleas living in Perry’s yard.
C. The liquid has changed the dog’s fur over time. Now the liquid is absorbed into the fur rather than staying on the skin.
D. Perry gives his dog a bath after applying the water resistant liquid and the liquid is not able to work correctly.