GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - F2M4L645H7I5ZZ9CK

The pepper Capsicum chinense grows as a native wild plant only in South America. Birds swallow the pepper's fruit whole, thereby providing the plant with its means of distributing seeds. Domesticated varieties of C.chinense grow in the Caribbean islands as well as in South America. Although it is unknown just when C.chinense was introduced into the islands, the introduction of the species was probably the result of human activity, because ________.