The Park Distance Control System Warns the Driver That the Vehicle

The park distance control system warns the driver that the vehicle is close to an obstacle by _____.

A) an audible signal that increases in frequency as the vehicle gets closer
B) the ABS system automatically applying the brakes when the vehicle gets too close
C) both "an audible signal that increases in frequency as the vehicle gets closer" and "the ABS system automatically applying the brakes when the vehicle gets too close"
D) neither "an audible signal that increases in frequency as the vehicle gets closer" nor "the ABS system automatically applying the brakes when the vehicle gets too close"