1.) It is essential to use many different types of equipment because you want to know what you are seeing and with this equipment you can you also want to make the right obversions like how bright or big a star is.
2.) The missing element would be oxygen. Since earth has carbon and oxygen it makes carbon dioxide so if a different planted has oxygen it will make it so people could breath on it.
hope i helped
D.theory.
Hypothesis is an idea or explanation of something that is based on a few know facts but that has not yet been proved to be true or correct.
While a theory is a formal set of ideas that is intended to explain why something happens or exists.
What causes hemolytic disease of the newborn (HDN)? HDN most frequently occurs when an Rh negative mother has a baby with an Rh positive father. When the baby's Rh factor is positive, like the father's, problems can develop if the baby's red blood cells cross to the Rh negative mother.
I believe the correct answer is homeostasis.
The first one would be temperature and salinity
the second one is convection.
