Let R be a relation on the set N of natural numbers defined by 'nRm $$\Leftrightarrow$$ n is a factor of m'. Then, which one of the following is correct?

If E is the universal set and A = B $$\cup$$ C, then the set E $$-$$ (E $$-$$ (E $$-$$ (E $$-$$ (E $$-$$A)))) is same as the set

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