The correct answer is option 'A', the Ghadr (Ghadar) was a revolutionary association of Indians with headquarters at San Francisco.

The Ghadr (Ghadar) movement was a significant part of India's struggle for independence against British colonial rule. It was founded by Indian nationalists in 1913 with the aim of overthrowing British rule in India. The movement derived its name from the Urdu word "ghadr," which means revolt or rebellion.

The Ghadr movement was primarily based in North America, particularly in San Francisco, where the movement's headquarters were located. The association consisted of Indian immigrants, mainly Punjabis, who had settled in the United States and Canada. These individuals were driven by a strong sense of nationalism and a desire to free their motherland from British oppression.

The movement aimed to mobilize Indians living abroad to actively participate in the struggle for independence. It published the Ghadar newspaper, which served as a platform to disseminate revolutionary ideas, inspire patriotism, and unite Indians against colonial rule. The newspaper was published in several languages, including Punjabi, Hindi, Urdu, and English, to reach a wider audience.

The Ghadr movement organized various activities to support the cause of Indian independence. It held meetings, protests, and demonstrations, and also established training centers to provide military training and educate its members about revolutionary ideologies. The movement sought to create a sense of solidarity among Indians and build a network of revolutionaries both within and outside India.

The Ghadr movement played a crucial role in shaping the nationalist movement in India. Its members were involved in planning and executing revolutionary activities, including armed uprisings against the British. Although some of these attempts were unsuccessful, the movement succeeded in raising awareness about the need for independence and inspiring future generations of freedom fighters.

In conclusion, the Ghadr (Ghadar) was a revolutionary association of Indians with headquarters at San Francisco. It was a significant part of India's struggle for independence and played a crucial role in mobilizing Indians living abroad to actively participate in the fight against British colonial rule.