Vernon is studying the population of deer in a tract of forest. He gathers the following data. Birth rate: -50 deerlyear
Death rate: -70 deerlyear
Which additional observation would support the conclusion that the deer population is NOT changing size from year to year, meaning that the net population change is 0?
A
If a deer survives its first year of life, its average life span is 20 years.
B
The average lifespan of a member of the deer population is 20 years.
С
About 20 deer per year immigrate to the tract of forest
D
About 20 deer per year emigrate from the tract of forest.