Final answer:
A mayfly follows an r-strategy for reproduction, characterized by large numbers of offspring and minimal parental care, unlike K-strategists such as humans, robins, and zebras.
Step-by-step explanation:
The organism that follows an r-strategy for reproduction among the choices provided is b. mayfly. This strategy is characterized by having a large number of small offspring, little to no parental care, and a life cycle that is often adapted to unpredictable or changing environments. Mayflies epitomize this strategy as they reproduce in large numbers and the adults usually have a very short lifespan, which precludes the possibility of providing long-term parental care. In contrast, the long developmental times and extensive parental care associated with humans, robins, and zebras mark them as K-strategists.