This contract is made by and between A Co. (hereinafter called “the seller”) and B Co. (hereinafter called “the buyer”), （） the seller is willing to sell the buyer the commodities listed （） on the terms and conditions stipulated below. Now these presents

This contract is made by and between A Co. (hereinafter called “the seller”) and B Co. (hereinafter called “the buyer”), （） the seller is willing to sell the buyer the commodities listed （） on the terms and conditions stipulated below. Now these presents witness that it is （） agreed between the parties hereto as follows.
A.whereas, hereinafter, therefore
B.whereby, whereof, thereinafter
C.whereby, hereinbefore, hereby
D.whereas, hereunder, hereby
正确答案：D