Rear Suspension what to replace?

[LastSVXintheChi]

Hey guys i was just curious about something...i have asked several people this and i have had 3 different answers so im hoping to get some help here

my rear suspension is getting real saggy and i want to know if i need to replace both struts and springs or just struts or just springs or neither. the ass is riding real low and the other day the rear tire started rubbing when i had 4 people in the car. there really isnt any bounce like the front.

one guy told me to do both because the springs in the back aren't as "strong" as the springs in the front

another just the struts because thats all i did in the front and they were fine

someone else you dont need to replace them until **** starts dragging XD (i thought this was funny)

thanks in advance