Final answer:
The joint type with unrestricted movement in a car-like mobile robot with an RRPR robot arm on an infinite plane is the revolute joint (option a).
Step-by-step explanation:
The joint type with unrestricted movement in a car-like mobile robot with an RRPR robot arm on an infinite plane is the revolute joint (option a).
In the given scenario, the prismatic joint has limits, meaning it allows movement along a single axis and has restrictions on its range of motion. On the other hand, a revolute joint allows rotational movement around a stationary axis, providing unrestricted movement in a 2D plane.
This type of joint would be ideal for a car-like mobile robot to achieve different arm configurations and orientations.