Nevin negotiates a deal for the sale of twenty$-$five acres of farmland to Otis. Nevin promises to hold the offer open in return for a small payment, but does not state an exact period of time. With respect to this offer

a$.$

the deal is done.

b$.$

a reasonable period of time is implied.

c$.$

the deal is binding except for the promise to hold the offer open.

d$.$

the offer must be held open for an indefinite period.