**Core Concept**
The Employees' State Insurance (ESI) program is a social security and health insurance scheme for Indian workers. It is a self-financing health insurance scheme that provides medical, disability, and other benefits to insured persons. The ESI program is funded through contributions from both employers and employees.

**Why the Correct Answer is Right**
In the ESI program, the employer's contribution is 4.75% of the wages payable to an employee. This contribution is mandatory and is paid by the employer on behalf of the employee. The employer's contribution is used to fund the medical and other benefits provided to the insured persons. The employer's contribution is a significant part of the ESI fund, which is used to provide a wide range of benefits, including medical treatment, disability benefits, and old age benefits.

**Why Each Wrong Option is Incorrect**
**Option A:** 5.75% is incorrect because it is higher than the actual employer's contribution. The actual contribution is lower than this amount.
**Option C:** 3.75% is incorrect because it is lower than the actual employer's contribution. The actual contribution is higher than this amount.
**Option D:** 2.75% is incorrect because it is significantly lower than the actual employer's contribution. The actual contribution is higher than this amount.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the ESI program is a self-financing scheme, and the contributions from both employers and employees are used to fund the benefits provided to the insured persons. The employer's contribution is a significant part of the ESI fund, and it is essential to pay the correct amount to avoid any penalties or legal issues.

**✓ Correct Answer: B. 4.75%**