The circle with a radius of one unit is partitioned into eight equal arcs, where each arc corresponds to specific values. Determine the value of the trigonometric function at the given real number using the (x,y) coordinates in the diagram or specify that the expression is undefined.

$\csc\left(\frac{7\pi}{4}\right)$

• A. $-2$
• B. $2$
• C. $\sqrt2$
• D. $-\sqrt2$

Answer: (D)