A frog uses little energy to produce a high number of offspring with which she spends little time. She is assured of her lineage due to the high probability that some of her offspring will survive. A human has (typically) only one offspring at a time but devotes a high amount of energy and resources to ensuring its survival. The human is assured of their lineage due to the high probability that each one of their individual offspring will survive, even if they have very few.
Work Step by Step
A chicken produces several offspring and invests somewhat more time and energy into them, protecting them when they are at their most defenseless only. The chicken is at a middle ground of investment between the human and the frog. The less an animal protects its young, the more offspring it needs to have in order to be assured the species will survive and their own genetic lineage will carry on. These are different strategies, but all are effective.