Which one of the following reasons does not affect the formation of a contract?

A． A、
There is no consensus between the parties over the essential terms of the contract.
B． B、
There is preliminary negotiations but no mutual assent reached.
C． C、
The contracting parties did not reach an agreement on non-materials terms.
D． D、
The manifestation of intent between the contracting parties are unanimous on the essential terms of the contract.