If A = {x : x is a multiple of 2}, B = {x : x is a multiple of 5} and C = {x : x is a multiple of 10}, then A $$\cap$$ (B $$\cap$$ C) is equal to

If we define a relation R on the set N $$\times$$ N as (a, b) R (c, d) $$ \Leftrightarrow $$ a + d = b + c for all (a, b), (c, d) $$\in$$N $$\times$$ N, then the relation is

Let S be the set of all persons living in Delhi. We say that x, y in S are related if they were born in Delhi on the same day. Which one of the following is correct?

Consider the following in respect of sets A and B.

1. (A $$-$$ B) $$\cup$$ B = A

2. (A $$-$$ B) $$\cup$$ A = A

3. (A $$-$$ B) $$\cap$$ B = $$\phi$$

4. A $$ \subseteq $$ B $$\Rightarrow$$ A $$\cup$$ B = B

Which of the above are correct?