Which of the Following Shows the Use of the Doctrine

Which of the following shows the use of the doctrine of promissory estoppel?

A) Lam contracted to supply Jones with steel.Before the steel was delivered,Lam's supplier increased the price.Lam could use the doctrine to force Jones to pay more to Lam.
B) Lee,a defendant,can use this doctrine as a defence against a plaintiff insisting on his full legal right when he had promised to forgive Lee some of Lee's legal obligation and Lee had relied on that promise.
C) This doctrine can be used by a plaintiff to enforce a written promise that has been signed and sealed (i.e.,a seal has been affixed next to the signature of the promisor) .
D) Val told Jim that she would give him her printer.If she doesn't,Jim could use the doctrine to force her to do so.
E) George rented a video and watched it with Elaine.She thought the movie was great and said that she'd pay half the rental price.George could use the doctrine to force her to pay as she promised.