Provide an Appropriate Response $( a , z )$ And $( - 5 a , 7 z )$

Multiple Choice

Provide an appropriate response.
-What is the midpoint of the segment joining $( a , z )$ and $( - 5 a , 7 z )$ ?

A) $( - 2 a , 4 z )$
B) $( - 4 a , 8 z )$
C) $( 2 a , 3 z )$
D) $( - 3 a , 4 z )$