A dependent variable is how they are recording, measuring or keeping track of the science experiment their doing.
A independent variable is the things/types there using to compare what is the most/least affective in the experiment.
A controlled variable is something that stays the same in the experiment or a group/set used for comparison
Harmful because they change how the genes are supposed to form and they can give disorders at times.
It is D
:D =-O :-P ;-) :-( :-) :-! :-$ B-) :O :-* :-D :'( :-\ O:-) :-[