Explanation:

Let’s break this down:

- Varun finishes the work in 28 days, so he does 1/28 of the work each day.

- Sarvesh is 40% more efficient. That just means he does work faster.

- To find his speed: 1.4 × Varun's efficiency = 1.4 × (1/28) = 1/20 per day.

- So, Sarvesh will finish the work in 20 days.

Here’s a quick look at the options:

- 18 days: Too quick, he’s not *that* much faster.

- 16 days: Even faster—doesn’t fit the 40% boost.

- 20 days: Makes sense mathematically.

- 15 days: Way too quick for just a 40% increase.

So, Option 3—20 days—is correct.