单选题 Although scientists have______long the human appendix as______organ, there is a growing body of evidence indicating that the appendix does in fact have a significant function as a part of the body's immune system.

• (A) overestimated … a minor
• (B) discounted … a vestigial
• (C) valued … a major
• (D) ignored … a pivotal
• (E) studied … an inaccessible