Write an Equivalent Double Integral with the Order of Integration $\int _ { 0 } ^ { 1 } \int _ { 0 } ^ { \tan ^ { - 1 } x } d y d x$

Multiple Choice

Write an equivalent double integral with the order of integration reversed.
- $\int _ { 0 } ^ { 1 } \int _ { 0 } ^ { \tan ^ { - 1 } x } d y d x$

A) $\int _ { 0 } ^ { \pi / 4 } \int _ { \tan y } ^ { \pi / 2 } d x d y$
B) $\int _ { 0 } ^ { \pi / 4 } \int _ { \tan ^ { - 1 } y } ^ { \pi / 2 } d x d y$
C) $\int _ { 0 } ^ { \pi / 4 } \int _ { \tan y } ^ { 1 } d x d y$
D) $\int _ { 0 } ^ { \pi / 4 } \int _ { \tan ^ { - 1 } y } ^ { 1 } d x d y$