The term for the number of years necessary for a population to double in size, given its current rate of growth, is
a. doubling time.
b. demographic transition.
c. growth rate.
d. growth time.

The term for the number of years necessary for a population to double in size, given its current rate of growth is doubling time. This is usually used to population, inflation, consumption of goods, and many other things that is expected to grow over time.

The answer would be letter A.

The changes to agriculture in the united states since 1900 is that increased mechanization has increased food production, thereby increasing the need for labor. there has been an increased need for higher speeds of food production due the fact that the population in the united states continues to rise.