Urea, $$\text{CO(NH}_2)_2$$, decomposes at $$90^\circ\text{C}$$ as $$\text{CO(NH}_2)_2(aq) \to \text{NH}_4^+(aq) + \text{OCN}^-(aq)$$. Experimental data obtained for the reaction is given in the following plot

From the graph it can be inferred that

A

Average rate of the reaction is the same for successive time intervals of 10 h

B

unit of rate constant of the reaction is $$\text{h}^{-1}$$

C

rate constant of the reaction is the lowest at 30 h

D

the reaction is of zero order