Final answer:
The rotation of a rectangular plate can have different types of angular speeds, but in this case, the correct answer is variable angular speed.
Step-by-step explanation:
The rotation of a rectangular plate can have different types of angular speeds depending on the situation. The correct answer to the question is a) Variable angular speed, as the angular speed can change during the rotation. For example, if we consider a merry-go-round increasing from rest to a constant rotational speed, the angular speed will vary as the merry-go-round accelerates.