Here, $\dfrac{a_1}{a_2} = \dfrac{3}{6} = \dfrac{1}{2}$, $\dfrac{b_1}{b_2} = \dfrac{4}{8} = \dfrac{1}{2}$, $\dfrac{c_1}{c_2} = \dfrac{5}{7}$.
Since $\dfrac{a_1}{a_2} = \dfrac{b_1}{b_2} \neq \dfrac{c_1}{c_2}$, the lines are parallel. → (A)
When $\frac{a_1}{a_2} = \frac{b_1}{b_2} \neq \frac{c_1}{c_2}$, the pair is inconsistent (no solution) and the lines are parallel. Always compare all three ratios to distinguish between parallel and coincident lines.