Final answer:
The major purpose of Otis’ pamphlet was Independence advocacy, aiming to convince the colonists to support a republican government and independence from British rule.
Step-by-step explanation:
The major purpose of Otis’ pamphlet was C) Independence advocacy. James Otis Jr. was a central figure in the intellectual underpinnings of the American Revolution and his pamphlets, including those arguing against the Writs of Assistance, were pivotal in rallying support against British colonial policies. In the context provided, it is clear that the pamphlet referenced aimed to persuade the colonists to reject monarchy and the British Empire in favor of an independent republican form of government, which was also a sentiment strongly echoed in Thomas Paine's influential work Common Sense.