`\mathbb{R}` is a set of all real numbers. If a relation `\rho` over set `\mathbb{R}` is defined such that `\rho = {(a,b) \in \mathbb{R} \times \mathbb{R} : ab \gt 0}`. Then relation `\rho` is -- (a) reflexive & symmetric, but not transitive,  (b) symmetric & transitive, but not reflexive,  (c) reflexive & transitive, but not symmetric,  (d) equivalence relation. 