The work of breathing is:

Correct Answer: A

Rationale: Work of breathing (WOB) is energy to overcome elastic (compliance) and resistive (airway) forces. Compliance (C = ΔV / ΔP) measures lung stretchability low C (stiff lungs) raises pressure needed, increasing WOB; thus, WOB is inversely related to compliance, true. During exercise, WOB rises with ventilation demand, not constant false. Airway resistance (R) directly increases WOB (e.g., asthma), contradicting not affected' false. In pulmonary fibrosis, low compliance elevates WOB, not reduces it false (emphysema might lower elastic work). The inverse compliance link (WOB = ∫P dV, P rises as C falls) is fundamental, reflecting effort to expand stiff lungs, making it the correct statement, critical for understanding respiratory workload in disease.

Correct Answer: B

Rationale: Nitrogen (N2) is the most abundant gas in Earth's atmosphere, comprising ~78% by volume, due to its chemical stability and geological accumulation. Oxygen (O2) is ~21%, vital for life but secondary. Argon (~0.93%) and carbon dioxide (CO2, ~0.0407%) are trace gases, with CO2 critical for climate despite low abundance. Nitrogen's dominance results from its inert nature and massive release during Earth's formation, per atmospheric composition data (e.g., NOAA). It dilutes other gases, shaping atmospheric pressure (~1013 hPa), making it the correct choice, far exceeding oxygen or trace constituents in prevalence.

Correct Answer: B

Rationale: The lateral nasal wall receives sensory innervation from trigeminal branches. The anterior ethmoidal nerve (A, V1) supplies the anterior upper part, the anterior palatine (C, greater palatine, V2) the posterior lower part, and the posterior superior lateral nasal nerve (D, V2) the posterior upper region. The posterior ethmoidal nerve (B, V1) innervates the posterior ethmoidal sinuses and upper nasal septum, not the lateral wall, which is served by other branches. Its role is sinus-specific, making B the exception.

Correct Answer: B

Rationale: Terminal bronchioles (B) lack goblet cells, lined by simple cuboidal with club cells, unlike olfactory (A, specialized), epiglottis (C), and false cords (D). B is the exception.

Correct Answer: C

Rationale: Neural crest cells, an ectodermal derivative, give rise to melanocytes (A), Schwann cells (B), and adrenal medulla (D). Melanocytes produce pigment, Schwann cells myelinate peripheral nerves, and the adrenal medulla forms chromaffin cells for adrenaline. Pia mater (C), the innermost meninges, derives from neural tube mesenchyme (possibly mesodermal or ectodermal, but not neural crest). Neural crest contributes to peripheral nervous system and pigment cells, not central meninges. C is the exception its origin outside neural crest lineage distinguishes it from the others.