As Property Manager of a 15-Unit Apartment Block,you Receive Rent

Multiple Choice

As property manager of a 15-unit apartment block,you receive rent payments on the first of every month from each tenant.Mrs.Lone,in apartment,whose rent is $500 per month,lost her job and was in dire financial difficulties.You agreed to take only $400 per month.For the last ten months,she has paid only $400 a month,but you have learned that for 4 months she has had a new and even better-paying job.You are angry that she failed to tell you this and you want to sue her for the entire amount of back rent ($1000) .Which of the following arguments could she use most effectively against you?

A) promissory estoppel
B) mistake
C) undue influence
D) breach of contract
E) duress