The correct answer is D. He trained the soldiers to be more disciplined and professional.
Step-by-step explanation:
Friedrich Wilhelm von Steuben was a military officer during the 18th century, mainly known for his role during the American Revolutionary War. Friedrich Wilhelm von Steuben was born in Prussia but he served as General in the Continental Army against Great Britan. Indeed, in 1778 von Steuben arrived at Valley Forge, which was one of the main military encampment but also one with the hardest conditions and in there supported the Continental Army mainly by training soldiers and modifying aspects in the encampment to make the army more discipline, professional, organize and stronger. Thus, Friedrich helped ease the hardships at Valle Forge by training the soldiers to be more disciplined and professional (Option D).