sequence of credit utilisation?

Section 35- says about Payment of Tax, It says thata) credit of IGST shall be first utilised for payment of IGST then for CGST and last for SGST b) Credit of CGST shall be first utilised for CGST then for IGST. c) Credit of CGST shall not be used for SGST d) Credit of SGST shall be first utilised for SGST then for IGST. e) Credit of SGST shall not be used for CGST