C. The law during his era required that plays be written in this meter.
Explanation:
Shakespeare's sonnets are prominently written in Iambic pentameter. It involves a rhyme scheme that employs ten syllables in each line of the sonnet with five pairs of iambs where one unstressed syllable is followed by a stressed syllable. His plays too engaged this meter as it was the order or style of the day. In fact, Shakespeare is known for his consistency in the employment of meter that added richness to his works and makes him a great writer. This meter was the most common verse meter of the time that Shakespeare used in his blank verse, sonnets, etc.
