W is registered for sales tax. The managing director has asked four staff in the accounts department why the output tax for the last quarter does not equal 20% of sales (20% is the rate of tax). Which one of the following four replies she received was not correct?
A．The company had some exports that were not liable to sales tax.
B．The company made some sales of zero-rated products.
C．The company made some sales of exempt products.
D．The company sold some products to businesses not registered for sales tax.