In a Goldfish Population, the Fitness of the Population Is

In a goldfish population, the fitness of the population is greater (that is, survival rate is higher) when the school of goldfish is larger.This is evidence of a(n)

A) Allee effect, in which larger numbers attract more predators.
B) Allee effect, in which larger numbers enable better group protection.
C) density-dependent effect, in which larger numbers result in greatly limited resources.
D) density-dependent effect, in which goldfish are responding to interspecific competition.
E) density-independent effect, in which goldfish are responding to an environmental factor.