Task: Question Answering
Input (English): Question: If a, b, c are consecutive positive integers and a<b<c, which of the following must be true?
I. c+a=b+a+1
II. abc is an even integer
III. (a+b+c)/3 is an integer

 Option A: I

 Option B: II

 Option C: I and II

 Option D: II and III

 Option E: all are true
Output (English): Option E