Passage 2

Michael Horan wrote the letter mainly to show that________.

推断题。根据题干定位到第一封信。这封信的开头“…many cyclists behave dangerously. Many drivers are disrespectful of cyclists. But pedestrians are probably the worse offenders”虽然涉及A、B两项，但显然But后的内容才是Michael Horan的目的所在：行人才是马路上最糟糕的违规者，即行人威胁交通安全。故本题选C。