Final answer:
The best option to replace the question mark is D. The 'non-cooperation' effort encouraged Indians to become self-sufficient.
Step-by-step explanation:
The best option to replace the question mark in the given sentence is D. The 'non-cooperation' effort encouraged Indians to become self-sufficient.
Gandhi's call for non-cooperation with the British government and British products was a key component of his strategy for achieving independence for India. This strategy aimed to promote self-sufficiency and reduce dependence on British goods, thus weakening British control over India.
By advocating for Indians to boycott British products and remove their children from British-run schools, Gandhi aimed to undermine British economic and educational control over India, furthering the cause of Indian independence.