The correct answer is: C. 28%
The Integrated Goods and Services Tax (IGST) is a tax levied on inter-state supply of goods and services. The rate of IGST is 28%. However, there are certain goods and services that are exempt from IGST, such as food items, education, and healthcare.
The other options are incorrect because they are not the rates of IGST. Option A, 12%, is the rate of Central Goods and Services Tax (CGST). Option B, 18%, is the rate of State Goods and Services Tax (SGST). Option D, 40%, is the rate of Union Territory Goods and Services Tax (UTGST).
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