The seventh-grade class is building target areas for a PE activity. The bases for the game will be circular in shape. The diameter of each circle is 5 feet. Approximately how many square feet of the turf needs to be painted for a base circle? Explain your resoning.
1. 15.7 square feet
2. 19.6 square feet
3. 42.8 square feet
4. 78.6 square feet