HELP，题目看不懂啊。are each equal to one more than the middle digit是什么意思？

proteus

13. If a 3-digit integer is selected at random from the integers 100 through 199, inclusive, what is the probability that the first digit and the last digit of the integer are each equal to one more than the middle digit?

   (A) 2/225

（B）1/111

  （C）1/110

（D）1/100

（E）1/50

Wilt

是不是D？ 好像只有101这个数

william1119

个位和百位均比十位大1！！！！！！

proteus

非常感谢！