During 1960's Banshi and his fellow peasant workers organised committees to fight back against the atrocities and oppressions of their landlords. This social movement strived to change the existing social and political arrangement. What is this kind of movement called?

The correct option is Revolutionary.

To understand why this is the correct classification, we can analyze the characteristics of different social movements:
1. Revolutionary Movements: These movements aim to completely overthrow the existing social and political systems and replace them with fundamentally new structures. They target dominant power relations (such as the landlord-peasant feudal relationship) to bring about systemic change. In the scenario, Banshi and his fellow peasant workers organized committees to fight back against landlords with the goal of changing the existing social and political arrangements entirely. This makes it a revolutionary movement.
2. Reformist Movements: These movements seek to change specific, limited aspects of the existing social or political system rather than replacing it entirely. They work within the established legal and political framework to bring about gradual improvements.
3. Redemptive Movements: These focus on changing the inner consciousness or personal lives of individuals rather than changing social structures (for example, religious conversion movements).
4. Radical/Alternative Movements: Alternative movements seek partial change in individual behavior (such as advocating for organic farming). While "radical" describes the nature of the change, "Revolutionary" is the standard sociological categorization for a movement aiming to completely alter the structural arrangements of society.

Since Banshi and his fellow workers strived to transform the fundamental power dynamics and dismantle the landlord system, the movement is classified as Revolutionary.