The correct answer is A. 28.
GST is a consumption tax that is levied on the value added to goods and services at each stage of the supply chain. It is a destination-based tax, which means that the tax is levied in the state where the goods or services are consumed.
GST is collected across five tax slabs that falls in 0%, 5%, 12%, 18% and 28%. However, the charges across products and SGST and CGST cannot exceed 28%. This is because the SGST and CGST are levied on the same base, and the total GST cannot exceed the value of the goods or services.
Option B is incorrect because it is the maximum rate of SGST.
Option C is incorrect because it is the sum of the maximum rates of SGST and CGST.
Option D is incorrect because it is greater than the maximum rate of GST.