This doesn’t capture the author’s advocacy for a focus on indigenous techniques as a way of protecting heirloom crops. In addition, the author doesn’t advocate for the preservation of heirloom crops for the purpose of protecting North American cultures.

This doesn’t capture the author’s advocacy for more attention and research directed toward indigenous techniques for preserving heirloom crops. In addition, we don’t know that indigenous farmers created hybrid crops “to maximize yields.” The purpose was to create different varieties, not to maximize yield.

This best captures the author’s advocacy for a focus on indigenous techniques for growing heirloom crops as a way to help solve the problem of North America’s rapidly eroding genetic base of crops.

Not supported. The author never suggests that indigenous knowledge caused the erosion of North America’s crop genetic base. Since (D) is not supported, it can’t be the main point.

Not supported. The author never suggests that heirloom crop genetics maintained by indigenous farmers results from an attempt to secure greater crop yields. In fact, the author indicates that maximizing crop yields is not conducive to genetic diversity in crops.