Bones of the human forearm and adjacent structures

Steps:

• Identify the forearm as the region from elbow to wrist, containing radius (lateral) and ulna (medial) bones.
• Note that diagrams of the forearm often include the distal humerus from the upper arm at the elbow joint.
• Exclude the scapula, which is the shoulder blade in the upper limb but not part of the arm or forearm.
• Match the three bones: humerus (upper arm), radius, and ulna (forearm).

Why A is correct:

• The humerus connects to the radius and ulna at the elbow, forming the three primary bones shown in forearm diagrams per standard anatomy.

Why the others are wrong:

• B includes scapula, the shoulder bone, not in the forearm or elbow.
• C includes scapula, irrelevant to forearm bones.
• D repeats C's error with scapula instead of humerus.

Final answer: A