JEE Math Practice Question

Let $$\mathrm{R}$$ be a relation on $$\mathrm{N} \times \mathbb{N}$$ defined by $$(a, b) ~\mathrm{R}~(c, d)$$ if and only if $$a d(b-c)=b c(a-d)$$. Then $$\mathrm{R}$$ is

1. A.symmetric and transitive but not reflexive
2. B.reflexive and symmetric but not transitive
3. C.transitive but neither reflexive nor symmetric
4. D.symmetric but neither reflexive nor transitive