Life expectancy refers to:-

The correct answer is Option (1) → The estimated number of years that an average person is expected to survive

Option (1) The estimated number of years that an average person is expected to survive — Correct. Life expectancy refers to the estimated number of years that an average person is expected to survive. It is calculated from data on age-specific death rates in a given area over a period of time.

Option (2) Total number of live births that a hypothetical woman would have if she lived through the reproductive age — Incorrect. This describes the total fertility rate, a measure of births, not of how long people live.

Option (3) Difference between birth rate and death rate — Incorrect. This is the rate of natural increase, or the growth rate of population.

Option (4) The number of live births per 1000 women in the child bearing age group — Incorrect. This is the fertility rate, usually taken for women aged 15 to 49 years.