(A) 0 or √3 (B)0 or 3 (C) 1 or √3 (D) 1 or 3.

Analysis: aub = a

∴B is a subset

So: m=3 or m = √ m

1) When m=3, a = {1, 3, √ 3} and b = {1, 3} satisfy the meaning of the question;

2) When m=√m, that is, m=0 or 1.

1') When m = 0, a = {1, 3,0} and b = {1, 0} satisfy the meaning of the question;

2') When m = 1, a = {1, 3, 1} does not satisfy the mutual anisotropy of the set, so it is discarded.

To sum up, m=0 or 3, and the answer is B.

Forget it after the exam! Play until the results come out! Hope to adopt!