**Core Concept**
The principle of respondent superior is a legal concept that holds an employer liable for the actions of their employees, provided they are performed within the scope of their employment. This principle is essential in medical malpractice cases, where a hospital or healthcare organization may be held accountable for the mistakes of its staff.

**Why the Correct Answer is Right**
The principle of respondent superior is applied by employers to ensure that they are responsible for the actions of their employees. This principle is based on the idea that employers have a duty to supervise and control their employees, and that they should be held accountable for any harm caused by their employees' actions. In medical settings, this principle is often applied to hold hospitals or healthcare organizations liable for medical errors committed by their employees.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because respondent superior is not primarily applied by government agencies, although they may be held liable in certain circumstances.
**Option B:** This option is incorrect because respondent superior is not a principle applied by insurance companies, although they may provide coverage for employers in case of liability.
**Option C:** This option is incorrect because respondent superior is not a principle applied by individual employees, although they may be held personally liable in certain circumstances.

**Clinical Pearl / High-Yield Fact**
The principle of respondent superior is a critical concept in medical malpractice law, and healthcare providers should be aware of its application to avoid liability for employee actions.

**Correct Answer:** D. Employers.