Jack wrote this expression to describe how much he will pay for flowers.

5 × f

which situation could be described by this expression?

a.
jack knows that he will buy 5 blue flowers. he does not know how many yellow flowers he will buy.

b.
jack knows that each flower costs $5. he knows that he will buy 5 flowers.

c.
jack knows that the flowers cost a total of $5. he does not know how many flowers he will get.

d.
jack knows he will buy 5 flowers. he does not know how much each flower costs.