Find the Exact Value of the Real Number Y $\mathrm { y } = \arctan ( 1 )$

Find the exact value of the real number y.
- $\mathrm { y } = \arctan ( 1 )$

A) $\frac { 3 \pi } { 4 }$
B) $\frac { \pi } { 3 }$
C) $\frac { 2 \pi } { 3 }$
D) $\frac { \pi } { 4 }$