**Core Concept**
The patient is undergoing a stress test to assess cardiovascular function, and the drug used for this purpose must be able to increase heart rate and contractility while maintaining or increasing blood pressure. This requires a pharmacological agent that acts on the adrenergic receptors, specifically the beta-adrenergic receptors, to produce a positive inotropic effect.

**Why the Correct Answer is Right**
Dobutamine is a synthetic catecholamine that acts as a beta-adrenergic agonist, primarily stimulating the beta-1 receptors in the heart, which increases heart rate and contractility. It also has some alpha-adrenergic agonist activity, which helps to maintain or increase blood pressure. Dobutamine is commonly used in stress testing, particularly in patients who are unable to perform a treadmill test due to physical limitations, such as amputation of both limbs. The increased heart rate and contractility produced by dobutamine allow for an assessment of cardiac function under stress.

**Why Each Wrong Option is Incorrect**
**Option A:** Dopexamine is a dopamine analogue that primarily stimulates the dopamine-1 receptors, which increases cardiac output and reduces peripheral resistance. However, it is not the first-line agent for stress testing and may not provide the same level of heart rate and contractility increase as dobutamine.

**Option B:** Dopamine is a catecholamine that stimulates various adrenergic receptors, including alpha-1, beta-1, and beta-2 receptors. While it can increase heart rate and contractility, its effects are more pronounced at higher doses, and it may cause significant vasodilation, which can lead to hypotension.

**Option D:** Dipevefrine is not a commonly used or recognized pharmacological agent, and it is likely a distractor in this question.

**Clinical Pearl / High-Yield Fact**
When selecting a medication for stress testing, it is essential to choose an agent that can safely and effectively increase heart rate and contractility while maintaining or increasing blood pressure. Dobutamine is a reliable choice for this purpose, and its use is well-established in clinical practice.

✓ Correct Answer: C. Dobutamine