Galileo
<span>his observations helped support the Copernican view that the planets orbited the Sun, and not the Earth as previously believed.</span>
Well, there is only one realistic answer. Option One is when you take the DNA of two different people or creatures and combine them into one organism. Cloning wouldn't prove anything here, "hybridization" is weird - but it doesn't have anything to do with the situation. So only only remaining option is DNA Profiling - also known as DNA Mapping, which shows the DNA structure and order that can be seen the same way in siblings (slightly different of course but it is still the right answer).
The variable that researchers manipulate is the independent variable.
The reason for this is because in experiments different manipulations are often introduced. The sole purpose of these manipulations is to see whether they will affect our independent variable and if they will change its value.
