Which of the following best exemplifies a positive feedback loop?

• A. Predation reduces prey numbers, stabilizing the system
• B. Migration patterns affecting seasonal resource availability
• C. Temperature fluctuations reinforcing climate cycles
• D. Breastfeeding and oxytocin

Answer: (D)

A positive feedback loop is a process in which the outcome of a reaction increases the original stimulus, causing the response to intensify as long as the trigger continues.

Breastfeeding and oxytocin fit this because suckling stimulates nerves that signal the brain to release oxytocin. Oxytocin then triggers milk ejection, making it easier for the baby to feed. The easier feeding reinforces the stimulus to suck, leading to more milk release and even more suckling. This creates a self-amplifying cycle that pushes the system toward the completion of the feeding session, rather than a stable point.

The other scenarios describe interactions that don’t continuously amplify a single response in a self-reinforcing way. They may involve regulation, cycles, or shifts that don’t drive the process to greater intensity in the same feedback manner.