Final answer:
Equilibrium is the dimension of physical abilities that includes sensations of position and movement of the head, aiding in balance and spatial orientation.
Step-by-step explanation:
The dimension of physical abilities you are asking about is c) Equilibrium. Equilibrium refers to a sense of balance and includes sensations of position and movement of the head, which is crucial for maintaining posture and orientation in space. It is part of proprioception, which is the awareness of the position and movement of the body. This sense helps organisms respond to changes in their internal and external environments, such as moving towards food or away from danger. Physical abilities like response orientation, rate control, and sense of direction are also important but equilibrium specifically refers to the capacity to maintain balance and spatial orientation.