单选题 What is the largest prime factor of 255?
  • (A)5
  • (B) 15
  • (C) 17
  • (D)51
  • (E)255


【正确答案】 C
【答案解析】Test the choices starting with C: 255 is divisible by 17 (255 = 17 × 15), so this is a possible answer. Does 255 have a larger prime factor? Neither Choice D nor E is prime, so the answer must be Choice C.