The correct answer is: C. 18%
The Integrated Goods and Services Tax (IGST) is a tax levied on inter-state supply of goods and services. It is a destination-based tax, which means that the tax is levied at the place where the goods or services are consumed. The rate of IGST is 18%.
The other options are incorrect because they are not the rates of IGST. Option A is the rate of CGST, which is a tax levied on intra-state supply of goods and services. Option B is the rate of SGST, which is a tax levied on intra-state supply of goods and services by a supplier registered in a state other than the state of consumption. Option D is the rate of GST on imports. Option E is incorrect because there is a limit on the rate of IGST.
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