Which best explains parallel forces? check all that apply.
*left and right forces that can be added together
*right and upward forces that cancel each other out
*upward and downward forces that can be added together
*left and downward forces that cancel each other out
*addition of parallel forces that cannot result in a negative force
*differences in parallel forces that result in a net force of zero

The answer is:

- left and right forces that can be added together  

-upward and downward forces that can be added together

The explanation:

-when the parallel force system is a situation in which two forces of equal magnitude act in the same direction within the same plane,

-and the parallel forces lie in the same plane and have lines of action that never intersect each other. Two forces that are parallel can either be in the same direction or in opposite directions.

and the only 2 phases that satisfy this definition are:

- left and right forces that can be added together  

-upward and downward forces that can be added together

because growing process had stoped after 4-5 year