Pick out the most effective word/phrases from the given alternatives marked (a), (b), (c), (d) and (e) given below each sentence to fill in the blank to make the sentence meaningful and grammatically correct.

By the time he was eighteen years old, Peter _______ to make a living and support his family.

A. begins

B. began

C. started beginning

D. would begin

Please do not use chat terms. Example: avoid using "grt" instead of "great".