Final answer:
Infanticide is the act of an adult killing a young animal of its own species. It is different from brood parasitism, where a bird lays its eggs in another's nest and is unrelated to parental care variations across species. Option b is correct.
Step-by-step explanation:
Infanticide refers to when an adult kills a young animal of its own species. It's a serious behavior that occurs in nature, often influenced by various biological and ecological factors. While caring for the young is vital for the survival of most species, some animals exhibit the darker side of nature through infanticide, and this can be observed among mammals and birds.
For instance, male lions are sometimes known to kill offspring that are not their own to bring the females back into estrus so they can father their own offspring. However, this concept is distinct from brood parasitism, where a bird lays its eggs in another bird's nest, letting the host raise their young, which is not considered infanticide.
The term also should not be confused with behaviors where animals kill members of other species, or related concepts such as exponential growth in populations or parental care in bird species like the Great Frigatebird.