Question

He _____________ rate is the level at which a population remains stable.

Answer 1

The replacement rate is the level at which a population remains stable.  
Replacement rate (level) is the fertility rate and represents the average number of children born per woman at which a population exactly replaces itself from one generation to the next (without migration). More precisely, it is the amount of fertility needed to keep the population the same, from generation to generation. As a result of the total fertility rate, there will be no increasing or decreasing of the population, it will be stable.