A loop carrying current `I` lies in the ` x-y ` plane as shown in the figure . The unit vector ` hat k` is coming out of the plane of the paper . The magnetic moment of the current loop is
A. `a^(2) I hat(k)`
B. `((pi)/(2)+1)a^(2) I hat(k)`
C. `-((pi)/(2)+1)a^(2) I hat(k)`
D. `(2pi +1)a^(2) I hat(k)`
