It is impossible to prove a fact until we are 100% certain and in the case of source D proving that A and B were successful in persuading men we cannot be, although it is indeed likely. The photograph may also have been staged; there are many other reasons why it does not prove anything in particular to us. .
In the US, the citizens were a little more reluctant to enrol, caused by not only the appalling casualties in Europe, but also due to the virtual lack of any military tradition in the states", the total amount of reserves being merely 32,000, insufficient even to operate large scale manoeuvres, thus in the US, of the 3,097,000 men recruited, only 517,000 were volunteers. So, was the number of enlisters due simply to opposition, or was the enormous difference between the number of volunteers numbers recruited due to something else? No doubt the complete effectiveness of controlling the population through propaganda had a considerable effect, (referred to in Q 4,5,6,7b and 8) however, pictures from around the country such as source D were a regular occurrence. Whole streets of friends joining up in "pals" battalions, which, although exceptionally successful in promoting recruitment, though were disastrous on days like 1st July 1916, where whole towns lost the flower of their manhood for an entire generation. Indeed, the attacks on the Somme, and many other dismal affairs like it, Passchendaele for example, may well have not been possible, bar such unscrupulous recruitment practices, many of the enlisting Sergeants allowing underage enlistment, "smiling they wrote his lie: aged 19 years", (Disabled) sending five different sets of brothers from Eton alone, to their premature deaths. Death, as taught in such establishments, was not one of dehumanising pain where, "eyes writhe in his face" (Dulce Et Decorum Est) after a gas attack, but rather one of Greek and Roman victories together with the "Esprit de corps" and of "daggers in plaid socks" (Disabled).