Final answer:
Izard's finding that infants respond emotionally supports the evolutionary cause of emotion.
Step-by-step explanation:
The finding by Izard that infants respond emotionally is used to support the Evolutionary cause of emotion. According to evolutionary psychology, emotions have a genetic basis and have evolved over time due to their adaptive value. Infants' emotional responses can be seen as an innate and instinctual behavior that has been shaped by natural selection.