I believe that the answer is actually the last one, B
B) When my science teacher allowed me to choose my own project, I got a better grade than I have ever gotten before in science class.
This is because the sentence says, “If students are allowed to design their own courses of study, they will be more engaged in the learning process and, therefore, more likely to succeed.” and it's basically saying that the students need to have a study course that they are actually interested in, only then would they actually learn something out of the lessons.
I know this is like, 3 years late, but if someone else needs an answer for this, I hope it helps. ^-^