单选题 The primary purpose of the passage is to

• (A) point out that theories about the functioning of olfactory sensation have failed to change despite experimental inquiry
• (B) suggest means by which the impact of odors that irritate human subjects may eventually be lessened
• (C) describe the attempt of scientists to understand the degree to which odor perception is learned or innate
• (D) demonstrate that efforts to understand the psychobiological basis for human perception is too difficult for modern laboratory techniques
• (E) describe how the emotional pairing process in odor sensation can lead to the experience of irritation