D is the answer
One way : Since you know that the average of the 4 people is 85% you can see that the fourth person has to be higher than 85% because 2 of the 3 known test scores is lower. By using process of elimination you would get 95%
Another way (mathematical way): Add 70+75+100+95= 340 dived that by 4. 340/4= 85
Hope this helped sorry it was late