Pain associated with intermittent claudication is caused by which of the following?

A. Bacterial overgrowth of highly contagious S. aureus with development of vesicles and pruritus is incorrect because this description applies to impetigo, which is a superficial bacterial skin infection. Psoriasis is an autoimmune condition and is not contagious, so bacteria are not the primary cause.

B. Abnormal T-cell activation leading to excessive growth of keratinocytes and rapid epidermal shedding is correct because psoriasis is driven by dysregulation of the immune system. In this condition, T-cells become overactive and release cytokines that stimulate keratinocyte proliferation at an accelerated rate. Normally, keratinocytes take about 28–30 days to mature and shed, but in psoriasis, this process can occur in 3–5 days. The rapid turnover results in thickened, scaly plaques, redness, and inflammation. Chronic inflammation also contributes to the pruritus, discomfort, and erythema seen in affected areas. Triggers such as stress, infections, or certain medications may exacerbate the condition but do not cause it directly.

C. Sensitization on first exposure to an allergen with rash development on subsequent exposure is incorrect because this describes allergic contact dermatitis, where the immune system reacts to a previously encountered allergen. Psoriasis, in contrast, is autoimmune and does not require prior allergen exposure. The lesions are caused by internal immune dysregulation, not external sensitization.

D. Latent virus becomes reactivated by infection or stress, leading to development of skin lesions is incorrect because this mechanism describes viral conditions such as shingles (herpes zoster). Psoriasis is not caused by a virus, and the plaques and scales result from keratinocyte hyperproliferation due to immune dysregulation rather than viral reactivation.

A. Bradypnea and slow heart rate is incorrect because pulmonary embolism (PE) usually triggers tachypnea and tachycardia, not slow breathing or bradycardia. These responses occur as the body attempts to compensate for hypoxemia and reduced pulmonary blood flow.

B. Bilateral peripheral edema and generalized weakness is incorrect because bilateral leg swelling is more characteristic of heart failure or systemic venous congestion. While a PE may result from deep vein thrombosis (DVT), edema is usually unilateral and not the defining manifestation of an acute PE.

C. Sudden onset of dyspnea and sharp chest pain is correct because a pulmonary embolism occurs when a blood clot obstructs a pulmonary artery, causing abrupt impairment of blood flow to the lung. This leads to sudden shortness of breath, sharp or pleuritic chest pain (worsening with inspiration), tachypnea, and sometimes hemoptysis. Other signs may include anxiety, diaphoresis, and hypoxemia. Rapid recognition is essential, as PE can be life-threatening if untreated.

D. Gradual onset of a productive cough with thick sputum is incorrect because this pattern is more typical of pneumonia or chronic bronchitis, not pulmonary embolism. PE symptoms are typically acute and sudden rather than gradual.