请教PREP 15题could的时态问题

15.   (25405-!-item-!-188;#058&001909)

Even though sub-Saharan Africa often evokes images of drought and famine, researchers say that the area is the home of more than 2,000 grains, vegetables, roots, fruits, and other foods that have the possibility for feeding the continent, even other parts of the world.

(A) have the possibility for feeding the continent, even

(B) have the possibility of feeding the continent, even of

(C) could feed the continent, so even with

(D) could feed the continent and even

(E) could possibly feed the continent and, in addition, for even

答案是D

答案是D

但是我不太明白D的话could不是和原句时态冲突吗，我记得情态动词里只有might和may可以互换，其他情态动词都要考虑时态的啊.

请高手指点

以下是引用snake37在2009/8/20 14:15:00的发言：
你管他时态呢！时态只有过去时和过去、现在完成时之间的选择的份！
是这样的：have the possibility 以及 be possible 没有could简洁，而且要注意：could不仅仅是can的过去式，它还有可能的意思！

噢，呵呵，多谢~我又好好查了一下字典，could确实可以用在一般现在时表达可能的意思