Area of a Circle

Winter has set in, and there is finally enough snow for Alex and his friends to start their monthly snow wars. Alex and his friends spend one Saturday a month having an intense snowball fight. Every year each team gets a corner of Alex's yard to create a fort. Alex has decided that he is going to build a giant circular fort this year.

Alex's yard is a square with an area of $64$ yards. Alex's fort can only fill $\frac{1}{4}$ of the area of his backyard. He is choosing between three different size forts:

• Fort A has a radius of $2$ yards
• Fort B has a radius of $2.5$ yards
• Fort C has a radius of $3$ yards