$\text { Find the value of the derivative (if it exists) of the function } f ( x ) = 15 - | x | \text { at the }$

Multiple Choice

$\text { Find the value of the derivative (if it exists) of the function } f ( x ) = 15 - | x | \text { at the }$ extremum point $( 0,15 )$

A) 13
B) 0
C) 15
D) $- 15$
E) does not exist