9. The 2025 Nobel Prize in Physiology or Medicine has been awarded in part to Dr Shimon Sakaguchi, Professor emeritus of Kyoto University. Professor Kawamoto, the Director of the Institute for Life and Medical Sciences, remarks: "Dr. Sakaguchi's strong commitment to achieving his research goals, in spite of at times facing daunting headwinds, no doubt has led to his great achievement." What does "headwinds" mean here? (A) headaches (B) obstacles (C) environmental issues (D) financial difficulties (E) supervisors