Correct Option (A):
Vishti, or forced labour, during the Gupta period was indeed considered a significant source of revenue or a form of tax for the State. Citizens, particularly from the lower strata of society, were compelled to render unpaid labour services to the state. This labour was utilized for various public works, including the construction and maintenance of roads, fortifications, and other state infrastructure, thereby contributing to the state's resources without direct monetary expenditure.
Incorrect Options:
Option (B): Historical evidence, including inscriptions and literary sources from the Gupta period, indicates that Vishti was prevalent across various regions of the empire, including Madhya Pradesh and Kathiawar. Therefore, the claim of its total absence in these regions is factually incorrect.
Option (C): Forced labour, by its very definition, involved compulsory service without remuneration. The labourers subjected to Vishti were not entitled to any wages, weekly or otherwise, for their services. This distinguished it from paid labour.
Option (D): There is no historical evidence or textual reference from the Gupta period to suggest a specific stipulation that only the eldest son of a labourer was sent as a forced labourer. The obligation for Vishti generally fell upon households or specific segments of the population as determined by local customs or state decrees, without such a precise familial rule.