Milk generation presently causes much more contamination than it utilized to, mostly because so much of the production is solidified into huge dairy ranches, and transfer of that kind of fluid squander is troublesome without harming adjacent water sources.
Answer:
The first question is answer A. The question asks for the independent variable, meaning this variable doesn't depend on any other variable. B is the dependent variable because the life span depends on the vitamin.
The second answer is A, the control group. It cannot be the other groups because they aren't real groups. Independent and dependent are variables, not groups.
Number one is y I think and number two is w. three should be x and four is z. I'm not sure though