vinni.k wrote:Is x = 0 ?

(1) xy = x
(2) x + y = y

Target question: Is x = 0 ?

Statement 1: xy = x
There are several pairs of values for x and y that meet this condition. Here are two:
Case a: x = 0 and y = 2, in which case x = 0
Case b: x = 3 and y = 1, in which case x = 3
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: x + y = y
Subtract y from both sides to get x = 0
In other words, x must equal 0
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer = B

Cheers,
Brent

vinni.k wrote: Why answer cannot be D. Statement (1) gives x = 0 or y = 1. It is giving x = 0. Why should we concerned about y = 1 when we are already getting x = 0 as it is being already asked ?

Good question, Vinni.

The problem is that you've reduced the strength of the question.
Yes, for statement 1, x could equal 0, but the target question doesn't ask, "Could x = 0?" The target question asks, "Does x = 0?"
In other words, "Must it be the case that x = 0?"

With all data sufficiency questions, a statement is sufficient if we are able to answer the target question with certainty.

In statement 1, we cannot answer the target question ("Does x = 0?") with absolute certainty, so it's not sufficient.

If you're interested, we have a free set of videos that cover everything you need to know about data sufficiency questions: https://www.gmatprepnow.com/module/gmat-data-sufficiency

Cheers,
Brent