Final answer:
Proximal describes a position nearest to the beginning of a structure or point of attachment, as in the brachium being proximal to the antebrachium. So, the correct option is a) nearest to the beginning of a structure.
Step-by-step explanation:
Proximal describes a position as being nearest to the beginning of a structure. It is a term used in anatomy to indicate a point on a limb that is closer to the point of attachment or the trunk of the body. For example, the brachium is proximal to the antebrachium, meaning it is closer to the shoulder in comparison to the forearm. This contrasts with distal, which indicates a position farther from the point of attachment or trunk of the body, such as the crus being distal to the femur, meaning the leg is farther from the hip than the thigh is.