Final answer:
The presence of the crop sac and ability to make crop milk does not determine whether only females can feed offspring. In these species, both males and females have crop sacs and can produce crop milk to feed their offspring.
Step-by-step explanation:
The presence of the crop sac and ability to make crop milk allows for only females to feed offspring.
This statement is false.
The crop sac and the ability to produce crop milk are characteristics found in certain bird species, such as pigeons and doves.
In these species, both males and females have crop sacs and can produce crop milk to feed their offspring.