Final answer:
The low fecundity of species like whales, humans, and elephants is likely due to 3) high investment in parental care.
Step-by-step explanation:
The most likely explanation for the low fecundity of species such as whales, humans, and elephants is high investment in parental care. These species produce relatively few offspring and provide extensive care to ensure the survival and development of their young. By devoting a significant amount of energy to parental care, these species prioritize the success of their few offspring over producing a large number of offspring. This strategy reduces the risk to the survival of the species when a single offspring dies and allows the parents to ensure the survival of their offspring.