`\mathbb{R}` is a set of all real numbers. If a relation `\rho` over set `\mathbb{R}` is defined such that `\rho = {(a,b) : a-b \lt 3, AA a,b \in \mathbb{R}}`, then the relation `\rho` is -- (a) transitive,  (b) equivalence,  (c) reflexive,  (d) symmetric.