The answer to this should be C -- both A and B are correct. That is, as long as B refers to indirect taxes on businesses.
National income is a measure of how much income businesses and households get from using productive resources in a given year.
The way that you calculate national income is to take GNP or GDP and then subtract depreciation and indirect business taxes from the gross national or domestic product.
You can also get this number by adding up various sorts of income, but in terms of your question, the formula where you subtract things from GDP or GNP is all that matters.