(A) Correct: The 1901 Census of India, headed by Herbert Risley, was a crucial moment in the colonial construction of caste. Risley attempted to scientifically classify and rank castes based on anthropometric measurements, solidifying caste hierarchies and furthering colonial administrative aims. While the question mentions the 1903 census, which didn't occur, the intent is to refer to Risley's influential role in the 1901 census. The 1911 census was also done under his supervision.
(B) Incorrect: Extensive information on caste, including social hierarchy, was collected in colonial censuses. This data was used to categorize and control populations, allocate resources, and reinforce existing power structures.
(C) Incorrect: While the colonial administration sometimes implemented policies seemingly aimed at the welfare of lower castes, these were often driven by political motives like divide and rule rather than genuine concern. The focus was not really on uplifting these castes.
(D) Incorrect: The Government of India Act of 1935, not 1950, introduced separate electorates and reservations for certain castes and tribes. The Constitution of India, adopted in 1950, continued and modified these provisions, recognizing Scheduled Castes and Scheduled Tribes and providing affirmative action policies.