$($Consideration of sunk and opportunity costs$)$ Hewlett$-$Packard has designed a new type of printer that produces professional$-$quality photos. These new printers took $2$ years to develop, with research and development running at $$10$ million after taxes over that period. Now all that's left is an investment of $$22$ million after taxes in new production equipment. It is expected that this new product line will bring in free cash flows of $$5$ million per year for each of the next $10$ years. In addition, if Hewlett$-$Packard goes ahead with the new line of printers, the current production facility for the old printers that are to be replaced with this new line could be sold to a competitor, generating $$3$ million after taxes.

a$.$ How should the $$10$ million of research and development

a$.$ How should the $$10$ million of research and development be treated? $($Select the best choice below.$)$

A$.$ It should be included in the project's net cash flows as opportunity$-$cost cash flows.

B$.$ It should be excluded from the project's net cash flows as sunk costs.

C$.$ It should be excluded from the project's net cash flows as operating expenses.

D$.$ It should be included in the project's net cash flows as sales revenues.