Answer:
The correct answer is option A.
Explanation:
Tobacco seeds of the same species in this experiment placed in a controlled system except for the light exposure during the first week as petri dish A was covered or wrapped with moist paper while the petri dish B was not wrapped so the exposure of light affected the germination of the tobacco seeds.
As dish A was covered to exclude the light so that it has no impact of light exposure no matter for how long it was placed in the light whereas dish B has direct exposure to the light that affected the germination process.
Thus, the correct answer is option A.