Answer:
The football team members
Step-by-step explanation:
Concepts
A population is the entire collection of things that you will use to gather the data. Meanwhile, a sample is a specific group that you'll collect data from.
Application
We are asked to find the population of this survey. We gathered data from the high school football team, and the data showed that the average height as 5'11". Thus, the population is the football team members.