The work of breathing is:

Correct Answer: A

Rationale: Work of breathing inversely ties to compliance. Work = pressure × volume; low compliance (e.g., fibrosis, < 0.1 L/cm H2O) demands more pressure (Q40). Exercise raises work (B, false) via demand (O2 use 1-5%). Resistance (C, false) increases it (asthma, Q8). Fibrosis hikes work (D, false, Q1). A's relation unlike B's static claim matches energy cost (~1-2% basal metabolism), per physiology.

Correct Answer: D

Rationale: A bloody pleural effusion aligns with pulmonary embolus (A) and myocardial infarct (C) thus D (A & C). Embolus causes infarction, leaking RBCs into pleura; post-MI (e.g., Dressler's) involves hemorrhagic inflammation. Acute hemorrhagic pancreatitis (B) causes abdominal effusion, rarely pleural, and not typically bloody unless complicated. All' overextends pancreatitis lacks direct pleural linkage. Bloody effusions (RBC >10,000/mm³) signal vascular or inflammatory breach, distinguishing from transudates, critical in differential diagnosis via thoracentesis, a chest nursing focus.

Correct Answer: D

Rationale: Umbilication of a solitary pulmonary nodule's border (D) irregular, notched edge suggests malignancy (e.g., adenocarcinoma), reflecting aggressive growth. Dense (A), core (B), laminated (C), or flecked calcification often indicate benignity (e.g., granuloma, hamartoma) calcification patterns stabilize lesions. Malignant nodules lack uniform calcium, growing unevenly, key in CT analysis for biopsy decisions in chest oncology nursing.

Correct Answer: B

Rationale: Mediastinal emphysema air in mediastinum stems from tracheal perforation (B), e.g., trauma or barotrauma, leaking air (crunching sound, Hamman's sign). Collaterals (A) fit SVCS. Elderly debilitation (C) is nonspecific. Perforation's air escape is key, needing urgent imaging (e.g., CT), guiding intervention in chest emergencies.

Correct Answer: A

Rationale: Methotrexate, an antimetabolite, causes myelosuppression, hepatitis (A) folate inhibition suppresses marrow, damages liver (e.g., ALT >100 U/L). Protein defects (B) fit asparaginase. Neuropathy (C) is vincristine. Cystitis (D) is cytoxan. Psychosis is prednisone. Methotrexate's toxicity is key in nursing for leucovorin rescue and liver function tests.