The driver suddenly applied the brakes when he saw a . . . . . . . truck ahead of him.

static
solitary
stationary
immobile

The correct answer is: C. stationary.

The other options are:

  • A. static: not moving or changing.
  • B. solitary: alone or without others.
  • D. immobile: unable to move.

The driver suddenly applied the brakes when he saw a stationary truck ahead of him. This means that the truck was not moving, and the driver had to stop to avoid hitting it.