Classify each of the following as a sunk cost, an opportunity cost, or neither.
a. The firm has spent $1 million thus far to develop the next-generation robotic arm; it is now examining whether the project should continue.
b. A piece of ground owned by the firm can be used as the site for a new facility.
c. It is anticipated another $200,000 of R&D spending will be needed to work out the bugs of a new software package.