Find the Cotangent (If It Exists) of the Real Number $t = \frac { 5 \pi } { 4 }$

Find the cotangent (if it exists) of the real number $t = \frac { 5 \pi } { 4 }$ .

A) $- \frac { \sqrt { 2 } } { 2 }$
B) 1
C) $- 1$
D) 0
E) $\cot \left( \frac { 5 \pi } { 4 } \right)$ does not exist