Why were physical activity and caffeine and alcohol intake the controlled variables?

Controlled variable is a variable that was made constant in the research. That was because the controlled variables can influence the dependent or independent variable. If the variables is not made constant, it can alter the research result and made it invalid.

In this case, the caffeine and alcohol intake might alter the physical activity or the blood glucose so it should be controlled.

Might need you in a few weeks c:

Answer:

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.