Explanation:

Let's break down the problem step by step:

- 35% of the employees are officers, and the remaining 65% are workers.

- Let the average monthly salary of a worker be Rs W.

- Consequently, the average salary of officers will be Rs (W + 39,000).

- The combined average salary of all employees can be represented using the equation:

$$

\text{Combined Average} = 0.35 \times (W + 39,000) + 0.65 \times W

$$

- Equating the combined average from the officer's perspective, we get:

$$

W + 39,000 = 0.35 \times (W + 39,000) + 0.65 \times W

$$

- Solving this equation gives the difference between the average salary of an officer and a worker as Rs60,000.

- Option 4 is the correct answer: Rs60,000