The dependent variable in an experiment could be formally called the cause while the independent could be called the effect.
The answer is most simply A
There will be no dwarf pea plants in the first generation, because T is the dominant gene
I think the scientist distinguish whether an entity is living or non living be describing the single unit of life, the live cell that could multiply, reproduce and generate trough time also through ages. I hope you are satisfied with my answer and feel free to ask for more