The correct answer is D. All of the above.
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 composition scheme is a simplified tax regime for small taxpayers. Under this scheme, taxpayers are allowed to pay a fixed percentage of their turnover as tax.
The time of supply is the point at which a supply is deemed to have taken place for the purposes of GST. The time of supply is important for determining the applicable
rate of tax and the time limit for filing returns.Service tax is a tax levied on the supply of services. It was levied under the erstwhile Service Tax Act, 1994. However, with the introduction of GST, service tax has been subsumed under IGST.
Therefore, IGST deals with all of the above.