The correct answer is (D) To enroll or enlist, usually as a student in a university or college. To enroll, or admit (a student) to membership and privileges by enrolling, esp. in a college or university. To be enrolled as a member of a university or college.

Matriculate comes from Middle Latin matriculare (to register).

Examples of use:

• She will matriculate next year.
• Unlike his future associates, Bill matriculated at Oxford.