Final answer:
In the context of monogamous relationships in animals, it is most beneficial when males contribute significantly to parental care, as seen in many bird species.
Step-by-step explanation:
The truth about monogamous relationships in the animal world, specifically addressing option b. Monogamous relationships are most beneficial when males provide significant parental care to offspring. This is observed widely in many bird species where not only the female but also the male provides substantial care for the chicks. The monogamous system, defined as one male and one female paired at least for a breeding season and sometimes for life, as seen in gray wolves, benefits offspring survival. Instances of this include the mate-guarding hypothesis, the male-assistance hypothesis, and the female-enforcement hypothesis.
In monogamous systems, one male and one female are paired for at least one breeding season. This is observed in many bird populations, where both parents provide significant parental care to the offspring. The male's involvement in parental care is beneficial because it increases the chances of survival and success of the offspring. Monogamy does not necessarily mean that animals do not mate outside of the relationship, as there can be cases of extrapair copulations.