Which of the Following Is an Example of Hypothesis-Driven Research

Which of the following is an example of hypothesis-driven research?

A) You are interested in studying the effect of chocolate consumption on test grades.You hand out a chocolate bar to half of the people in the class and instruct them to eat it immediately prior to taking the test.After the test you analyze the grade distribution to see how grades were affected by chocolate consumption.
B) You are interested in studying the effect of chocolate consumption on test grades.You hand out a chocolate bar to everyone in the class and instruct them to eat it immediately prior to taking the test.After the test you analyze the grade distribution to see how these grades differed from the last exam when no one ate any chocolate.
C) You propose that the consumption of chocolate immediately prior to taking the biology midterm will result in a high grade.You hand out a chocolate bar to half of the people in the class and instruct them to eat it immediately prior to taking the test.After the test you analyze the grade distribution to determine if students who ate chocolate got higher grades than students who did not eat chocolate.
D) You decide that the consumption of chocolate immediately prior to taking the biology midterm will impact grades.You hand out a chocolate bar to half of the people in the class and instruct them to eat it immediately prior to taking the test.After the test you analyze the grade distribution to determine if students who ate chocolate got higher or lower grades than students who did not eat chocolate.