Final answer:
The end of slavery in Massachusetts was marked by Quock Walker's successful lawsuit for freedom and damages, aligning with the Massachusetts Constitution that affirmed equality and freedom for all.
Step-by-step explanation:
The case that marked the end of slavery in Massachusetts was Quock Walker's successful suit for freedom and damages after he was brutally beaten, making the correct answer D. This series of decisions in the 1780s significantly undermined slavery in Massachusetts after Walker invoked the new Massachusetts Constitution that declared all men were born free and equal. His legal victory against his owner was pivotal in influencing the state's courts to rule that slavery was inconsistent with the state’s new constitution.