If a, b, and c are consecutive positive integers and a < b < c, which of the following must be true?
I. c - a = 2
II. abc is an even integer.
III. (a + b + c)/3 is an decimal. Choose the correct choice.
A) I only	B) II only	C) I and II only	D) II and III only	E) I, II, and III
Since a, b, and c are consecutive positive integers and a &lt; b &lt; c, then c = a + 2, from which it follows that c - a = 2. So, I is true.   Next, out of 3 consecutive integers at least 1 must be even, thus abc=even. II is true.   Finally, since b = a + 1, and c = a + 2, then (a + b + c)/3 = (a + a + 1 + a + 2)/3 = a + 1 = integer. III is false.   Answer: I and II only
<result>C</result>
If a, b, and c are consecutive positive integers and a < b < c, which of the following must be true?
I. c - a = 2
II. abc is an even integer.
III. (a + b + c)/3 is an decimal.