JB Inc Sold a Piece of Equipment to SubSurf Ltd

JB Inc sold a piece of equipment to SubSurf Ltd for a total price of $240 000. Under the terms of their contract, SubSurf was required to pay $10 000 on the first day of each month for twenty- four months. The contract also stated that if SubSurf was late on any single payment, JB was entitled to demand immediate payment of the entire outstanding amount. SubSurf made the first four payments on time. For the next six months, however, it was habitually late by at least one week. JB did not object to receiving those late payments. However, when SubSurf did not pay the eighth instalment on the first day of the next month, JB demanded immediate payment of the entire outstanding amount. Which of the following statements is TRUE?

A) SubSurf must immediately make a lump sum payment of $240 000 to JB.
B) JB is estopped from complaining about the late payments as long as SubSurf can prove that it relied upon the fact that the first ten payments were accepted without objection.
C) The doctrine of promissory estoppel is inapplicable because it can only be used as a sword.
D) The doctrine of promissory estoppel is inapplicable because JB did not make an effective representation.
E) The parties' contract is invalid because SubSurf's promise to immediately pay the entire outstanding amount if it failed to perfectly comply with the repayment schedule was a gratuitous promise.