The Khudai Khidmatgars, also known as Red Shirts, was a non-violent resistance movement formed by Khan Abdul Ghaffar Khan against the British colonialism in India.

Option 1: This is incorrect as the main aim was not the union of Pashtun tribal areas in north-west with Afghanistan but to end the oppressive British regime.

Option 2: The Khudai Khidmatgars were known for their adherence to non-violence. Hence, they did not promote terrorist tactics to oust the colonial rulers.

Option 3: While the Khudai Khidmatgars embraced some principles aligning with communism, such as equality and justice, the adoption of communist revolutionary ideology was not their primary objective.

Option 4: This is the correct answer. The Khudai Khidmatgars stood for Pathan regional nationalist unity and they used non-violence and civil disobedience as their main tactics in the struggle against British colonialism. Hence, option 4 correctly identifies the primary focus of the Khudai Khidmagars during the Indian freedom struggle.