Find the Largest Open Interval Where the Function Is Changing $f ( x ) = \sqrt { 4 - x }$

Multiple Choice

Find the largest open interval where the function is changing as requested.
-Decreasing $f ( x ) = \sqrt { 4 - x }$

A) $( - \infty , - 4 )$
B) $( - \infty , 4 )$
C) $( - 4 , \infty )$
D) $( 4 , \infty )$