In Moss V Chin, Chin's Insurer, ICBC, Made an Offer to Settle

In Moss v. Chin, Chin's insurer, ICBC, made an offer to settle a claim that was accepted by the public trustee representing Mrs. Moss. ICBC was not aware that Mrs. Moss had died in the interim. ICBC made a unilateral mistake and yet the Court ordered that the contract be rescinded. What was the rationale?

A) There was no consideration to support the claim, and therefore the contract was invalid.
B) ICBC lacked capacity to make an offer, as only Chin had such a right.
C) ICBC had not misled itself, rather the public trustee had deliberately set out to keep ICBC from discovering the truth.
D) The public trustee lacked capacity to accept an offer, as only Mrs. Moss could do, and she had died.
E) It is illegal to settle a claim when the claimant is not longer alive.