The correct answer is: D. Both a and b
IGST is an integrated goods and services tax levied on inter-state supply of goods and services. It is a composite tax that subsumes central GST (CGST) and state GST (SGST). The tax is levied by the central government and collected by the state government. The revenue from IGST is shared between the central government and the state government in the ratio of 50:50.
CGST is a tax levied on intra-state supply of goods and services. It is levied by the central government and collected by the central government. The revenue from CGST is retained by the central government.
SGST is a tax levied on intra-state supply of goods and services. It is levied by the state government and collected by the state government. The revenue from SGST is retained by the state government.
The tax IGST charged by both central government and state government.