Which is the only long bone in the human body to lie horizontally?

Correct Answer: A

Rationale: The clavicle (A) is the only horizontal long bone (collarbone). Humerus (B) is vertical, scapula (C) is flat, and ischium (D) is pelvic.

Correct Answer: A

Rationale: The corpus callosum connects the left and right brain (A). Not skeletal-neural (B), brain-spinal (C, via brainstem), or thalamus-hypothalamus (D).

Correct Answer: D

Rationale: Bile enters the duodenum (D) via the bile duct. Cecum (A), jejunum (B), and ileum (C) are later in the tract.

Correct Answer: C

Rationale: The vulva (C) is primary female external genitalia. Gonads (A, ovaries) are internal, testes (B) are male, and uterus (D) is internal.

Correct Answer: A

Rationale: The nose (A) is anterior (front). Ears (B) are lateral, occipital lobe (C) is posterior, and temporal lobe (D) is lateral.