a. multiplying total income by the APC.
Explanation:
The income model is also known as a revenue model and it is a spreedsheets formula used by individuals or organizations to identify the best income source to explore, what goods and services to offer, pricing of these goods and services, and who is the target audience (consumers).
Total income can be defined as the overall amount of money that is being earned by an individual or a household before any deductions such as tax.
One can determine the amount of any level of total income that is consumed by multiplying total income by the average propensity to consume (APC).
An average propensity to consume (APC) is a measure of the amount of money as a percentage that is being consumed by an individual or household rather than being saved.
I think that is b in my opinion