Answer:
Explanation: nitrogen dioxide
Metaphase is the stage in which the "crossing over" occurs.
As we know chromosomes carry genetic information. This crossing over process happens in eukaryotic cells and occurs during the mitosis phases of cell division.
Hopefully this helped.
A hypothesis states a presumed relationship between two variables in a way that can be tested with empirical data. It may take the form of a cause-effect statement, or an "if x,...then y" statement. The cause is called the independent variable; and the effect is called the dependent variable.