I think it is letter c. adding a conjunction between the complete sentences. The other ones can be used on a run on sentence. Letter c. is an example of a bad way to fix a run on.
The correct element is B - evidence. Statistics and other examples can be used as evidence for a research paper.
The best answer for this question would be:
To achieve your dreams, you have to exercise, practice, and
make good choices.
In this big idea, the path to success leads to a lot of
practice and a lot of training from life experiences and even lessons from
different people, with that you can be able to make good choices.