Which option is an example of an experiment?
a. recording the reaction time of participants in a study who were
asked to press a button as soon as they see a certain picture on a
screen
o
b. testing the effect that eating organic food has on health by having
a group of people selected at random eat organic food for six
consecutive months and then comparing the results with a group
of people who didn't eat any organic foods during the same period
o
c. asking students in a school how much time they spend exercising
o
d. polling teenagers about their screen time in a day

B. Testing the effect that eating organic food has on health by having

a group of people selected at random eat organic food for six

consecutive months and then comparing the results with a group

of people who didn't eat any organic foods during the same period

3. parallelogram

step-by-step explanation:

we turn each of our sides into direction vectors

ab=b-a=(3 - 7, 1 - 0) = (-4, 1)

bc=c-b=(1,6)

cd=d-c=(4,-1)

da=a-d=(-1,-6)

we see how the opposite sides have negated direction vectors; this is characteristic of a parallelogram.   we have congruent sides ab=cd and bc=da with unequal lengths because 1^2+6^2 is different from (-4)^2+1^2.   so it's not a square or a rhombus.  

we check the dot product of direction vectors of adjacent sides.   we have

ab dot bc = -4(1) + 1(6) = 2

that's not zero so the sides are not perpendicular.   we've ruled out rectangle.

the direction vectors indicate two pairs of congruent parallel sides, so we choose parallelogram over trapezoid.

the function makes a strait line horizontally with no x intercept but a y intercept at 9.