Is the following reasoning correct & overlapping lines is not parallel

Question

Two lines y=mx+c, y=nx+d
two lines. Are they parallel?
a) m+n=4
b) m=n

v12345 · Answer

y=mx+c, Slope=m
y=nx+d, Slope=n

If slope is equal, lines are parallel.

(1) m+n=4 . Insufficient
m=n=2, parallel lines
m=1, n=3 , not parallel

(2) m=n . Sufficient
Parallel lines.

Hence, OA is (B).

HarshaBujji · Answer

The slope of the lines is m,n respectively;

If 2 lines are parallel then their slopes are the same.

So m=n is sufficient;

IMO B

sumitkrocks · Answer

Slope is same for two parallel lines 
I.e m = n

2nd statement is sufficient not first
Option(B) is correct IMO

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