Use the \( ( x , y ) \) coordinates in the figure to find the value of tan \( 2 \pi \) or state that the expression is undefined. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. \( 18 \) of \( 20,20 \) point(s) possible
A. tan \( 2 \pi = \)
(Simplify your answer, including any radicals. Use integers or fractions for any numbers in the possible expression. Rationalize the denominator. )
B. The expression is undefined.