Penny and nikki were assigned a lab activity to test the effectiveness of different stain removers. they took four shirts and stained each shirt with grape juice. each shirt was treated with a different stain remover per the directions on the bottle. after washing each item, they came to the conclusion that stain remover b was the best of the four for removing stains. if you were their science teacher, what advice would you give them to them better validate their findings? a) none. the experiment and conclusion were perfect. b) use fewer shirts and fewer stain removers. they tried to do too muchc) their conclusion should be specific to grape juice on that particular fabric. d) they should use something besides grape juice, because it is not a popular drink.