Which of the following shoes the use of the doctrine of promissory (equitable) estoppels?

a.Pooch told Nadia that he would give her his old boat. If he doesn't, Nadia could use the doctrine to force him to do so.

b.If Nadia accidentally ran her car over her neighbour's bushes, she could use the doctrine as a defence.

c.This doctrine can be used by a plaintiff to enforce a written promise signed and sealed (i.e., a seal has been affixed next to the signature of the promisor).

d.A defendant (e.g. Pooch) can use this doctrine as a defence against a plaintiff (e.g. Lui Peru) insisting on his full legal right when he had promised to forgive the defendant some of his obligation.