It is recommended that you submit drawings done from observation and not drawings that are copied from photographs. You are free to submit whichever you like but do note that, in addition to technique, you will be assessed on concept and originality and drawings copied from photos generally are not evaluated very high in those areas. It is fine to use photos as reference for part(s) of a drawing but, again, copying a photo in its entirety is not recommended. If you took the photos you are drawing from, perhaps you could just submit the photographs instead of the drawings.