**Core Concept:** The first-line treatment for a patient with chronic obstructive pulmonary disease (COPD) and concomitant hypertension should be targeted at managing both conditions simultaneously.

**Why the Correct Answer is Right:**

In this case, the patient presents with hypertension (148/92 mmHg) and hyperkalemia (potassium level of 5.6 mg/dL). Option D (ACE inhibitors) is the correct answer because ACE inhibitors are the primary medication used to treat hypertension, specifically targeting the renin-angiotensin-aldosterone system (RAAS). ACE inhibitors lower blood pressure by inhibiting the conversion of angiotensin I to angiotensin II, thereby reducing aldosterone secretion. This leads to decreased sodium and water reabsorption, resulting in vasodilation and decreased peripheral vascular resistance, which ultimately results in blood pressure reduction.

**Why Each Wrong Option is Incorrect:**

A. Calcium channel blockers (CCBs) are also used for hypertension management but are not the first-line choice due to their potential to worsen hyperkalemia by reducing potassium excretion.

B. Diuretics are often used for hypertension management, but they may exacerbate hyperkalemia by reducing potassium excretion and exacerbating hypokalemia.

C. Beta-blockers are used for hypertension but might worsen hyperkalemia due to their potential to reduce potassium excretion and cause hypokalemia.

**Clinical Pearl:** The choice of antihypertensive medications should consider the potential complications of each drug class and tailor the therapy to minimize adverse effects while achieving an optimal therapeutic response. This highlights the importance of considering the potential complications when selecting medications for patients with comorbidities.

**Correct Answer:** D. Angiotensin-converting enzyme inhibitors (ACE inhibitors) are the first-line treatment option for this patient due to their effectiveness in reducing blood pressure while minimizing the risk of worsening hyperkalemia.