With reference to forced labour (Vishti) in India during the Gupta period, which one of the following statements is correct?(2019)
a) It was considered a source of income for the State, a sort of tax paid by the people.
b) It was totally absent in the Madhya Pradesh and Kathiawar regions of the Gupta Empire.
c) The forced labourer was entitled to weekly wages.
d) The eldest son of the labourer was sent as the forced labourer.