In the following statements, which one is an opinion? A: Tuberculosis (肺结核) is a global epidemic. About 9 million new cases are diagnosed worldwide every year, one-quarter of them in Africa. B: Since it was first established in 1901, the Nobel Prize in physiology or medicine has been awarded 109 times to 216 scientists. C: Students would welcome a change in the school uniform policy. D: Harry Potter studies at Hogwarts School of Witchcraft and Wizardry.