Thirty minutes of exercise per day can reduce your blood pressure. Which of the following is a guideline for establishing causality? a) Look for evidence that smaller amounts of exercise produces a reduction in blood pressure.
b) Check if lower blood pressure is present or absent when exercise is present or absent
c) Perform a randomized, controlled experiment.
d) Control the number of minutes of exercise and blood pressure to get the same results.

opt. (d)

Step-by-step explanation:

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

you didn't give me the choices, so i will just give you the graph so you can look at your choices and choose the right one.