Which One of the Following Examples Best Illustrates the Concept

Which one of the following examples best illustrates the concept of baseline as behaviourists use the term?

A) Dimitri is afraid of the school swimming pool after he almost drowned in it one day.
B) Louisa likes the attention she gets from boys when she wears tight sweaters.
C) Marsha starts copying her best friend's homework assignments regularly after she finds out that she gets better grades if she does so.
D) Justin talks in class all the time, even though his teacher and classmates do nothing to encourage him.