If a, b, c are consecutive positive integers and a<b<c, which of the following must be true?
I. a-b is positive integer
II. ab is an even integer
III. (a+b+c)/2 is an integer
Choose the correct answer:
A) II only
B) I only
C) III only
D) II,III only
E) I,III only
a&lt;b, a-b is negative.   odd* even or even * even = even   1+2+3= 
<gadget id="calculator">1+2+3</gadget>
<output>6</output>
6/2= 
<gadget id="calculator">6/2</gadget>
<output>3</output>
3 is an integer   Answer : II,III only
<result>D</result>
If a, b, c are consecutive positive integers and a<b<c, which of the following must be true?
I. a-b is positive integer
II. ab is an even integer
III. (a+b+c)/2 is an integer