Which of the following statements is the most accurate when comparing a tumor supressing gene to the parts of a car?

a. Tumor suppressor genes are often likened to the gas pedal of a car.
b. Tumor supressor genes are often likened to the brake system of a car
c. Tumor supressor genes are often likened to the towing system of a car
d. Tumor supressor genes are often likened to the cooling system of a car