What is "the rule in Pinnel's case"? Which of the following is correct?

Question 7 options:

A)The rule under Pinnel's case is that the payment of a lesser sum cannot be good consideration for a promise not to sue for the remainder of the debt

B)In Pinnel's case a court decided that parties to a lending agreement can come to an arrangement they wish regarding an early payment of a debt; a lesser sum can be paid in full satisfaction of a pre-existing debt

C)Under Pinnel's case there is promissory estoppel not to sue for any remaining amounts owed if a party takes it upon themselves to pay out a debt earlier than expected

D)The rule of Pinnel's case is that any indication by a creditor that early payment is acceptable as discharge of a debt, is good reliable consideration for a promise of no further legal action