The option that addreses a more general intention of using the present tense is A, because It allows readers to experience events at the same time that the characters expierence it. For the immediacy of the present tense, the reader can notice a change as it happens, not after the fact. This helps to keep the story's climax in a high level and the intensity of the story as well.
The option b and c are characteristics included in the option A. If you experience the events as they happen your comprehension about what the character is feeling and doing, also the setting is broader and clear.
