Consider that a species of salmon lays 20,000 eggs per pair when it spawns and dies. At the end of five years, an average of one pair of mature salmon from this group of hatched eggs returns again to spawn in the parent stream (19,998 have died). What is the rate of natural increase?
A) zero, because there is exact replacement of the previous generation
B) -2,000, because there was this much average die-off per year
C) 10,000, because there were that many eggs produced per parent fish (r)
D) 2,000, because this must be divided by five years
E) -19,998, because there was this much total loss