Two blocks, of mass $\displaystyle {m}$ and $\displaystyle {2}{m}$, are initially at rest on a horizonatal frictionless surface. A force $\displaystyle {F}$ is exerted individually on each block, as shown above. The graph shows how $\displaystyle {F}$ varies with time $\displaystyle {t}$. Which block has the greatest average power provided to it between $\displaystyle {t}={0}$ s and $\displaystyle {t}={3}$ s?