The day I graduated from college, I was ecstatic. Though I was just 21 years old, I felt like I was suddenly part of the larger picture; I had become an adult. A productive member of my society. By doing all my homework, showing up for classes, studying hard, and succeeding in my major, I felt I had finally entered the real world.

Which of the following is a correction for the sentence fragment in the paragraph?

A) The day I graduated from college. I was ecstatic.
B) By doing all my homework.
C) I was a productive member of my society.
D) Studying hard. Succeeding in my major.