2. Make sure that the empty set φ does not contain any elements, so (1) and (2) are both wrong; An empty set is a subset of any set, so (3) is correct; Any set is a subset of itself, so (5) is correct; Two sets cannot be linked by "attribution", so (4) is wrong, so this question should choose B.

3. According to the conditions, there must be at least three elements in the set M, and 1 2 must have two elements, so the sets M that meet the conditions are {1, 2,3}, {1, 2,4} and {1, 2,3,4.