## Core Concept
The question tests the understanding of β-adrenergic receptors and their agonists. β1 receptors are primarily found in the heart and are involved in increasing heart rate and contractility. A selective β1 receptor agonist would specifically target these receptors.

## Why the Correct Answer is Right
The correct answer, , is a selective β1 receptor agonist. It works by directly stimulating β1 receptors in the heart, leading to an increase in heart rate and contractility. This is useful in certain clinical scenarios where an increase in cardiac output is desired without significantly affecting β2 receptors found in smooth muscle, which could cause unwanted vasodilation or bronchodilation.

## Why Each Wrong Option is Incorrect
* **Option A:** - This is incorrect because is a non-selective β agonist, stimulating both β1 and β2 receptors.
* **Option B:** - This option is incorrect as is known for being a β2 receptor agonist, used primarily for its bronchodilatory effects in asthma and COPD.
* **Option D:** - This is incorrect because is a β2 receptor agonist.

## Clinical Pearl / High-Yield Fact
A key point to remember is that (Dobutamine) is often used in clinical settings for its positive inotropic effect (increasing the contractility of the heart) and is a drug that medical students and professionals should be familiar with, especially in the context of acute heart failure or cardiogenic shock.

## Correct Answer Line
**Correct Answer: C. Dobutamine**