questioner wrote:

*n* = 2*m* × *k* (given) , if *k* = 1 and *m* = 2, then *n* = 4.

Based on statement (2) that is correct.

**Quote:**

*m* is NOT divisible by *m*. So, it is not sufficient as well.

It's not clear what you meant, but what the question asks us is:

**Quote:**

… is *n*²ª a multiple of *m*ª?

The proposed values make it "… is 4²ª a multiple of 2ª?"

And 4²ª is indeed a multiple of 2ª, so the proposed values do not prove statement (2) to be insufficient.