According to social exchange theory, altruistic behavior is guided by

the median of the data is 4.

step-by-step explanation:

the median means the middle number of a given number.

to decide which one is the median, arrange in ascending or descending order. but sometimes, you may find two(2) number in the middle, but it's easy, just add them together and divide by 2.

so,   determine the median of the data. 2, 3, 3, 4, 5, 7, 9

it is already arranged, count 3 times forward and 3 backward and the one left is your answer.

2,3,3,4,5,7,9

our answer is 4.

hope this !

haile selassie i was the emperor of ethiopia from 1930-1974

i only have part a but here is the first one: - lewis and clark are born

- lewis marries sacajawea and clark is jealous  

- clark drowns lewis and then goes to jail

answer; the trial de novo