Which One of the Following Is the Best Example of a Student

Which one of the following is the best example of a student attributing success to internal factors?

A) Nita has just gotten an A on her final exam in world history and is feeling very grateful to the teacher for her good grade.
B) Carole's teacher has just told her that she will be the group leader for her reading group next quarter.Carole is glad her teacher is in a good mood today.
C) Renata has just gotten a good grade on her math test and she is glad that her mother got her a math tutor.
D) Meg has just gotten a good grade on her geography test.She is proud that she did so well and glad that she studied hard.