The correct answer is D: a transverse wave.
When you illustrate wave motion by moving a rope up and down, you create a transverse wave, where the motion of the medium (the rope) is perpendicular to the direction of the wave's propagation. In a longitudinal wave (A), the motion of the medium is parallel to the direction of the wave. An electromagnetic wave (B) is not a mechanical wave, as it does not require a medium to propagate. Therefore, the best option illustrating wave motion with a rope is a transverse wave.