If y ≠ 3 and 2b/y is a prime integer greater than 2, which of the following must be true?
I. b = y
II. y = 1
III. b and y are prime integers.	Answers.
A) None B) I only C) II only D) III only E) I and II
Note that we are asked which of the following MUST be true, not COULD be true. For such kind of questions if you can prove that a statement is NOT true for one particular set of numbers, it will mean that this statement is not always true and hence not a correct answer.   So we should try to make the listed statements not true for some b and y (which satisfy y≠3 and 2b/y=prime&gt;2).   I. b = y --&gt; not necessarily true: b=3 and y=2 (2b/y=3=prime&gt;2);   II. y=1 --&gt; not necessarily true: b=3 and y=2 (2b/y=3=prime&gt;2);   III. b and y are prime integers --&gt; not necessarily true: b=10 and y=4 (2b/y=5=prime&gt;2).   Nonenswer: None.
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If y ≠ 3 and 2b/y is a prime integer greater than 2, which of the following must be true?
I. b = y
II. y = 1
III. b and y are prime integers.