According to the information given in the exercise, the pen for his rabbit is square and each side is 7 feet long.
You know that the formula for calculating the area of a square is:
[tex]A=s^2[/tex]Where "s" is the length of each side of the square.
In this case:
[tex]s=7ft[/tex]Then, you need to substitute this length into the formula and then evaluate, in order to find the area. You get:
[tex]\begin{gathered} A=(7ft)^2 \\ A=49ft^2 \end{gathered}[/tex]Hence, the answer is: Option A.