Data Sufficiency

Is a<b<c ?

1. a-1 < b < c+1

2. a+1 < b< c-1

OA:B

Source-Math Revolution

NandishSS wrote:Is a<b<c ?

1. a-1 < b < c+1

2. a+1 < b< c-1

Statement 1:
Let b=0.

Then:
a-1 < 0
a < 1.
c+1 > 0
c > -1.

Result:
a<1, b=0, c>-1.
It's possible that a=b=c=0, in which case the answer to the question stem is NO.
It's possible that a=-1, b=0 and c=1, in which case the answer to the question stem is YES.
INSUFFICIENT.

Statement 2:
Let b=0.

Then:
a+1 < 0
a < -1.
c-1 > 0
c > 1.

Since a<-1, b=0 and c>1, a<b<c.
The relationships in blue indicate that -- on a number line, regardless of the value of b -- a will always be MORE THAN ONE PLACE TO THE LEFT of b, and c will always be MORE THAN ONE PLACE TO THE RIGHT of b.
Thus, in every case, a<b<c.
SUFFICIENT.

The correct answer is B.