A Bird Sanctuary Sometimes Takes Over the Care of Eggs

A bird sanctuary sometimes takes over the care of eggs or chicks of an endangered duck species if the parents are killed. They are sometimes able to use mothers of farm ducks to cross-foster the chicks, but it doesn't always work. Looking at the following data table, what is the critical period for imprinting in this species? (Note: DAH stands for "days after hatching".)

A) The critical period extends from 1-3 DAH.
B) The critical period extends from 3-8 DAH.
C) The critical period ends sometime between 1-3 DAH. We can not determine from this data when the critical period begins.
D) The critical period ends sometime between 3-8 DAH. We can not determine from this data when the critical period begins.