The temperature coefficient of a reaction is :

Question

$(A)\;\text{The rate constant at a fixed temperature.} \\ (B)\;\text{The ratio of rate constant at two temperatures} \\(C)\;\text{The ratio of rate constant differeing by $10^{\circ}$ preferably at $25^{\circ}$ and $35^{\circ}C$ } \\(D)\;\text{None of these}$