In the Indian national movement, in which year did Mahatma Gandhi launch the Non Cooperation Movement against British rule?

Introduction / Context:
The Non Cooperation Movement was one of the first mass movements led by Mahatma Gandhi that drew large sections of Indian society into active participation against British rule. It marked a major shift from petition based politics to mass satyagraha and boycott on a national scale. Knowing the year in which this movement started is a fundamental fact for anyone studying modern Indian history or preparing for competitive exams.

Given Data / Assumptions:

• The movement mentioned is the Non Cooperation Movement.
• It was launched under the leadership of Mahatma Gandhi and the Indian National Congress.
• Four possible years are given: nineteen hundred, nineteen twenty, nineteen forty, and nineteen thirty five.
• The question focuses on the year of its formal beginning.

Concept / Approach:
The Non Cooperation Movement was launched in response to a series of events, including the Rowlatt Act of nineteen nineteen and the Jallianwala Bagh massacre. The Congress session at Nagpur and earlier decisions at Calcutta in nineteen twenty provided the framework for non cooperation. Therefore, the correct year to remember is nineteen twenty. Later mass movements like the Civil Disobedience Movement and Quit India Movement belong to the nineteen thirties and nineteen forties, so those options can be excluded.

Step-by-Step Solution:
Step 1: Recall that the Rowlatt Act and the Jallianwala Bagh massacre occurred in nineteen nineteen, creating widespread anger in India. Step 2: Mahatma Gandhi proposed a nationwide Non Cooperation Movement as a response to these injustices and to demand self rule. Step 3: The movement was formally approved by the Indian National Congress and launched in nineteen twenty. Step 4: Compare this with the options and note that nineteen twenty is present. Step 5: Reject the other years because they correspond to different phases of the freedom struggle, not the start of Non Cooperation.

Verification / Alternative check:
A standard timeline of the national movement lists Non Cooperation Movement under nineteen twenty to nineteen twenty two. The movement saw actions such as boycott of foreign cloth, surrender of titles, and non cooperation with government schools and courts. Since these activities are clearly dated to the early nineteen twenties, nineteen twenty is the only suitable starting year among the options.

Why Other Options Are Wrong:
1900: This is far too early and belongs to a period dominated by moderate leaders, long before Gandhi mass leadership in India.

1940: This year is closer to the time of the individual satyagraha and the buildup to Quit India, not to Non Cooperation.
1935: This relates more to constitutional developments like the Government of India Act nineteen thirty five, not to the movement in question.

Common Pitfalls:
Learners sometimes mix up the launch years of different Gandhian movements, especially Non Cooperation, Civil Disobedience, and Quit India. A simple memory aid is to remember the sequence as nineteen twenty for Non Cooperation, nineteen thirty for Civil Disobedience and the Salt March, and nineteen forty two for Quit India. Fixing these three in mind helps avoid confusion.

Final Answer:
The Non Cooperation Movement was launched in the year 1920.