The correct answer is option 3, which is Satyagraha in Champaran. In April 2017, India celebrated 100 years of Mahatma Gandhi`s Satyagraha movement in Champaran.

Satyagraha in Champaran was one of Mahatma Gandhi`s early acts of nonviolent resistance against British rule in India. In 1917, he arrived in Champaran, a district in Bihar, to support the farmers who were forced to grow indigo and were subjected to unfair treatment by the British landlords.

Gandhi organized peaceful protests and mobilized the farmers to resist the unjust indigo cultivation system. Through his Satyagraha movement, he encouraged the farmers to assert their rights and stand up against the oppressive British landlords.

This movement in Champaran was significant as it marked the beginning of Gandhi`s use of nonviolent resistance as a powerful tool for social and political change. It laid the foundation for his future campaigns and became a symbol of India`s struggle for independence.

In summary, option 3, Satyagraha in Champaran, is the correct answer as it represents the event India celebrated in April 2017, which marked 100 years since Gandhi`s nonviolent protest in Champaran against the indigo plantation