Control groups are used in experiments in order to A Control the effects of outside variables on the outcome. B Control the subjects of a study to ensure that all participate equally. C Guarantee that someone other than the investigators, who have a vested interest in the outcome, controls how the experiment is conducted. D Achieve a proper and uniform level of randomization. E Increase the variability in response variable.

A). Control the effects of outside variables on the outcome

Step-by-step explanation:

A control group may be defined as the group that keeps separated or isolated from the rest of the samples of the experiment. This is done because the independent variable that are being tested are not able to influence the results. It is an observation or experiment designed to reduce the effects of the variables other than independent variable. It  isolates the effects of the independent variable on the experiment and increases reliability of the results. Thus it controls the effects of the outside variables on the results of the experiments.

let's cover over the formula of the vertex:

y = a(x – h)^2 + k

in this formula, (h,k) are the vertex, always remember that the positive or negative value of the vertex is based on the sign it has.

for example, if the vertex is -3,-6 then both the x and y value would have the positive sign attached to it and if it were a positive x and y value, then a negative sign would be attached to it.

with that being said, for our problem the x value is a positive one so we are looking for a number with a negative sign next to it, in this case the first and second choice.

however, for the first answer choice it isn't quite part of the formula so we know that the answer choice correctly displays the x value.

to confirm, we can see if the -1 fits correctly with the second answer choice, and as mentioned above a negative number will have a positive sign attached to it. so, for our problem we can see that -1 has been changed to +1, so we can confirm that the second answer choice is correct.

hence, our final answer is y=(x - 1)^2 + 1