When the first signs of brake pad wear appear, what should we do?

When the first signs of brake pad wear appear, what should we do?
A)Wait to notice abnormal squeaks when braking.
B)Detect by direct observation if there is brake pad wear.
C)Replace the pads with new ones, as soon as the first signs appear.Correct
We must replace the brake pads with new ones at the first sign of wear because, otherwise, the brake discs could be irreparably damaged.