D would be the best answer. The larger hammer would have a greater mass indeed. So it would creat more friction between the nail and the hammer creating more force being applied to the nail. Therefore the nail being able to go into the wood.
Advantage:
They were fighting on their home country. (they didn't have to travel overseas)
Britain was fighting France at the same time as they were fighting the US
Disadvantage:
They didn't have a trained army.
They didn't have much $.
The Pacific Railroad Act stipulated that the Central Pacific Railroad Company would start building in Sacramento and continue east across the Sierra Nevada, while a second company, the Union Pacific Railroad, would build westward from the Missouri River, near the Iowa-Nebraska border.