A hypothetical reaction has a rate law of:

Rate $=\mathrm{k} \left[\mathrm{A}{]}^2\right[\mathrm{B}]$

Which statement about this reaction is most probably correct?

Doubling the concentration of A will double the rate of the reaction.

Tripling [A] will affect the rate twice as much as tripling [B].

The reaction mechanism involves the formation of  ${\mathrm{B}}_2$at some stage.

The reaction mechanism involves more than one step.