Which two factors could be controlled to make the result of the investigation more valid ​

its b. greenhouse gasses trap uv rays for heat so that the plants stay alive.

the statements that apply here about binary star system are

"have stars that might appear to wobble"

"often have one star that is brighter than other"

a binary star is a star system consisting of two stars revolving around their common barycenter. systems of two or more stars are called multiple star systems.

answer; synapse;