The correct answer is A. 3.7 years.
The capital recovery period is the number of years it takes to recover the initial investment in a project. In this case, the initial investment is Rs. 4.7 lacs and the annual savings are Rs. 1 lac. Therefore, the capital recovery period is 4.7 lacs / 1 lac = 4.7 years.
Option B is incorrect because it is the annual savings divided by the annual depreciation. The annual depreciation is not the same as the annual savings.
Option C is incorrect because it is the purchase price divided by the annual savings. The purchase price is not the same as the annual savings.
Option D is incorrect because it is the purchase price divided by the annual depreciation plus the salvage value. The annual depreciation is not the same as the annual savings, and the salvage value is not relevant to the capital recovery period.