Fact 1: Playing is just one of many ways that mammals and other animals learn how to behave.

Fact 2: People behave as a result of a complex interaction.

Given the two facts above, answer the question "What is a complex interaction shared by mammals and other animals?" with the following options: 
- seeing
 - firm hugs
 - food
 - staring
 - power
 - blinking
 - sound
 - playing


 

        playing 