Which of the following graphs represents exothermic reaction?

 

Rate law for the reaction $\mathrm{A}+2 \mathrm{B}⟶\mathrm{C}$ is found to be
Rate$=\mathrm{k}[ \mathrm{A}]\left[\mathrm{B}\right]$

Concentration of reactant ' $\mathrm{B}$ ' is doubled. Keeping the concentration of '$\mathrm{A}$' constant, the value of rate constant will be :

Compounds '$\mathrm{A}$' and '$\mathrm{B}$' react according to the following chemical equation 

$\mathrm{A}\left(\mathrm{g}\right)+2 \mathrm{B}\left(\mathrm{g}\right)⟶2\mathrm{C}\left(\mathrm{g}\right)$

Concentration of either '$\mathrm{A}$' or '$\mathrm{B}$' were changed keeping the concentrations of one of the reactants constant and rates were measured as a function of initial concentration. Following results were obtained. Choose the correct option for the rate equations for this reaction.