Hi,

This is a perfect example for trap question in GMAT.

Already someone has figured the trap.

Answer choice B would have been the obvious trap answer. Whenever anything look too obvious it’s better to cross check, may not every time it would be a trap answer, but it’s always better to have a another look at it.

I will give my 2 – cents to this question.

Question: Is A*B is even?

That is product of two numbers is it even?

Note that we don’t know anything about A and B,

These below three rules of addition and multiplication of integers will help.

Add or sub :Even + even = Even

Even + Odd = Odd

Odd + Odd = Even

Multiplication:Odd * odd = odd

Even * odd = even

Even * even = even.

So let’s get into the statements,

Statement I is insufficient:

A + B = 7

First of all here A + B is 7, with this we can’t really say whether A and B are integers,

Maybe here,

A = 3.5 and B = 3.5

Or it could be

A= 3 and B = 4.

So insufficient.

Statement II is insufficient.

B is even,

Here is where someone has to careful because it’s easy to fall for the trap here, because B is even then AB is even.

Note that: This is possible only when A and B is even.

We can get that B is an integer, but not really sure about A.

It could be,

A = ½ and B = 2, answer to the question would be NO.

Or

A = ½ and B = 4, Answer to the question would be YES.

Together it is sufficient,

A+B = 7,

Since B is even, A has to be odd to get the sum as odd integer.

So AB is even.

So together it is sufficient.

Answer is C.

Hope this helps

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