Groups of organs that work together to complete a process in the body are called:

cells
tissues
nerves
systems

Group of organs which work together to complete a process in the body are called as systems.  

There are five levels of organisation of living organisms, namely- Cell, Tissue, Organ, Organ system, and Organism. Organ system is the level of organisation which includes all those organs which are involved in related function.

Group of organs which collectively perform specific function make systems, also called the organ system.

Example- Circulatory system, Respiratory system, Nervous system, Excretory system.

option 3 . (5x + 1) - (-10x + 6)

step-by-step explanation:

option 1 :

(4x + 3) + (-9x + 4)

or 4x+3 -9x + 4

or -5x + 7

option 2

(x - 2) - (6x - 9)

or x-2-6x + 9

or -5x + 7

option 3

(5x+ + 6)

or 5x + 1 + 10x -6

or 15x -5

option 4

-4x+2x+7-3x

-7x + 2x + 7

-5x + 7

hence only option 3 did   not satisfy the given simplify expression.