17. In Passage B, it can most reasonably be inferred from the third paragraph (lines 74–79) that “centers of crop diversity” become crucially important when:
A. plant breeders would like to learn more about the plant species of central Asia.
B. problems with a cultivated crop require experts to research a new variety of the crop.
C. consumers would like more variety in grocery produce departments.
D. disputes among plant breeders, pathologists, and entomologists lead to a reduction in crop variety.