Define Rate of reaction and Average rate?

Question

$\begin{array}{1 1} \text{(a) Rate of reaction : It is defined as the change in concentration of reactant (or product) in unit time. Average Rate - $\large\frac{\Delta X}{\Delta T}$} \\ \text{(b) Rate of reaction : It is defined as the change in concentration of reactant (or product) in 100 seconds. Average Rate - $\large\frac{\Delta X}{\Delta T}$} \\ \text{(c) Rate of reaction : It is defined as the change in concentration of reactant (or product) in unit time. Average Rate - $\large\frac{\Delta X}{\Delta T^2}$} \\ \text{(d) Rate of reaction : It is defined as the change in concentration of reactant (or product) in unit time. Average Rate - ${\Delta X}\times {\Delta T}$} \end{array}$