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	Pick:  A) I  B) II  C) I and II  D) II and III  E) all are true
1. c+a=b+a+1 --&gt; a, b, c are consequitive positive integers and a&lt;b&lt;c then c+a=b+a+1. So this statement is always true;   2. abc is an even integer --&gt; out of any 3 consecutive integers at least one must be even thus abc=even. So this statement is also always true;   3. (a+b+c)/3 is an integer --&gt; the sum of odd number of consecutive integers is ALWAYS divisible by that odd number. So this statement is also always true. Or: (a+b+c)/3=(a+a+1+a+2)/3=(3a+3)/3=a+1=integer.   Answer: all are true.
<result>E</result>
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