Which physical features influence george washington's decision to choose valley forge as the location of the winter camp for his army? a) it was close to the port of boston for easier access to supplies. b) valley forge was located on canadian soil and by law the british could not attack his men there. c) the location's elevated ground and the schuylkill river to the north made the site easy to defend. d) valley forge is in southern pennsylvania and would have warmer winter temperatures than other locations further north.