Exp) Option c is the correct answer.

Statement I is correct: The Indian National Congress (INC) endorsed the program of non-cooperation at the Nagpur session in December 1920. At this session, an important change was made in the Congress. Now, instead of having the attainment of self-government through constitutional means as its goal, the Congress decided to have the attainment of swaraj through peaceful and legitimate means, thus committing itself to an extra constitutional mass struggle.

Statement II is correct: The Non-Cooperation movement was planned to be implemented in stages. The later phase of the movement involved resignation from government service, and non-payment of taxes.

• In the first phase from January to March 1921, the main emphasis was on the boycott of schools, colleges, law courts and the use of Charkha.
• This phase was followed by the second phase starting from April 1921. In this phase the basic objectives were the collection of Rs. one crore for the Tilak Swaraj Fund by August 1921, enrolling one crore Congress members and installing 20 lakh Charkhas by 30 June.
• In the third phase, starting from July, the stress was on boycott of foreign cloth, boycott of the forthcoming visit of the Prince of Wales in November, 1921, popularization of Charkha and Khadi, and Jail Bharo by Congress volunteers.
• In the last phase, since November 1921, a shift towards radicalism was visible. The Congress volunteers rallied the people and the country was on the verge of a revolt. Gandhi decided to launch a no-revenue campaign at Bardoli, and also a mass civil disobedience movement for freedom of speech, press and association.

Source:

A Brief History of Modern India, Spectrum, Chapter – 16, Non-Cooperation Movement and Khilafat Andolan, Pg. 332 – 334

https://egyankosh.ac.in/bitstream/123456789/89550/3/Unit-7.pdf (Pg. 95 – 96)