The allocation of seats in the present Lok Sabha is based on the 1971 Census. The Census is a comprehensive survey conducted by the Government of India every ten years to gather data about the country`s population. It includes information about various demographic factors such as age, sex, literacy rate, occupation, etc.

The allocation of seats in the Lok Sabha, which is the lower house of the Indian Parliament, is determined by the population of each state. The more populous a state is, the more seats it has in the Lok Sabha. This is done to ensure fair representation and proportional distribution of political power among the different states.

The allocation of seats in the Lok Sabha based on the 1971 Census means that the distribution of seats is based on the population figures collected during the 1971 Census. This allocation remains in effect until the next Census is conducted and new population figures are available.

It is important to note that the provided answer may not be accurate as the option should have mentioned the year of the Census on which the allocation of seats is based. Therefore, it is recommended to check with a reliable source or refer to the latest official government announcements to ensure the most up-to-date and accurate information regarding the allocation of seats in the present Lok Sabha.