Hub.com is considering a new product called A$-$Plus for its customers. However, the introduction

of this new product is expected to lower the revenues received from

Hub.com's existing lines of

products by $$100,000$ per month.

Which of the following is NOT true: the lowered revenues are considered?

a$.$ a sunk cost

b$.$ an opportunity cost

c$.$ a side effect

d$.$ an erosion

e$.$ a relevant cash flow