In the following examples, choose the correct answer using the dropdown menus:

a$.$ Doug works in a woodworking shop and has a choice between to activities: He can sand one rocking chair per hour or he can inspect two boards per hour. What is the opportunity cost of sanding one rocking chair?: inspecting two boards per hour, sanding one rocking chair per hour, sanding two rocking chairs per hour, inspecting $1/2$ board per hour.

b$.$ Sheila works the front desk in one of the buildings on campus. Every hour during her shift she has a choice between two activities: organizing $300$ files per hour or deleting $600$ emails per hour. What is the opportunity cost of organizing $300$ files? deleting $600$ emails per hour, delating two emails per hour, organizing $300$ files per hour, deleting $300$ emails per hour

c$.$ Griselda is a creative writer and has a choice between writing one more novel this year or five more short stories this year. What is the opportunity cost of writing just half a novel, in terms of short stories? writing $5$ short stories per year writing $1$ novel per year, wiring $2\mathrm{.}5$ short stories per year, writing $2\mathrm{.}5$ novels per year