With no explanation, chose the best option from "A", "B", "C" or "D". acceptance of an offer unless the effect of the silence is to mislead the other party.”)- There are exceptions to this rule, which are in essence forms of estoppel, but none of them apply here. First, silence may operate as acceptance if supported by the parties’ “course of conduct.” Russell v. Raynes Assocs. Ltd. P’ship, 166 A.D.2d 6, 569 N.Y.S.2d 409, 414 (1st Dep’t 1991). Howev er, this exception generally applies only where there is an ongoing course of conduct. See Restatement (Second) of Contracts § 69 (1981) (silence may operate as acceptance “where because of previous dealings or otherwise, it is reasonable that the offeree should notify the offeror if he does not intend to accept.”); Albrecht Chem. Co. v. Anderson Trading Corp., 298 N.Y. 437, 440-41, 84 N.E.2d 625 (N.Y. 1949) (<HOLDING>). This exception does not apply here because

A: recognizing that silence can operate as acceptance where the parties may have been advised and warned by a previous course of dealings that inaction would be taken as assent
B: holding mutual assent in contract law is elementary and it must be expressed by the parties
C: holding that under illinois law silence can constitute acceptance under the terms of the restatement of contracts
D: holding that the parties relationship was not lengthy enough to establish an ordinary course of dealings as the first transaction between the parties was subject to the preference action
A.