Mark's physics book is on the desk. Mark pushes horizontally (from the side) on the book, but the book does not move. Diagram A shows a box with a downward and upward arrow equal in size Diagram B shows a box with an arrow up, down, left, and right all equal in size. Diagram C shows a box with shortest arrow pointing left, equal arrows pointing up and down, and longest arrow pointing right. Diagram D shows a box with a downward and upward arrow with the downward arrow larger in size. Which force diagram represents the force on the physics book? You may neglect air resistance.