North Pacific Humpback Whale Populations Declined Dramatically Due to Hunting

North Pacific humpback whale populations declined dramatically due to hunting by humans.But when hunting was banned, the population grew from 1,400 whales in 1966 to almost 20,000 in 2006.This change was due to

A) removal of a density-dependent factor.
B) removal of a density-independent factor.
C) addition of a density-dependent factor.
D) addition of a density-independent factor.
E) addition of an artificial reproductive stimulus.