The correct answer is C. Jambs.
A jamb is the vertical side of a door or window opening. It is the frame that the door or window fits into. Jambs are typically made of wood, metal, or stone.
A reveal is the exposed area of a wall between the jamb and the framing. It is the space between the door or window and the wall. Reveals can be used to add decorative detail to a door or window opening.
A vertical is a line that runs up and down. It is perpendicular to a horizontal line. Verticals are often used in architecture to create a sense of order and stability.
None of these is not the correct answer.