Which of the Following Is a Null Hypothesis for the Research

Which of the following is a null hypothesis for the research topic Are there differences in final class grades between students who are taught psychology in a lecture format or self-paced?

A) There are differences in final class grade between students taught psychology in lecture versus self-paced format.
B) There are no differences in final class grade between students taught psychology in lecture versus self-paced format.
C) Students taught psychology in lecture format receive higher class grades than those in self-paced conditions.
D) Students in self-paced conditions have higher class grades in psychology than those in lecture classes.