What did Baron Friedrich von Steuben contribute to the American cause at Valley Forge? A
supplies and weapons

B
personal finances

C
skills training for soldiers

D
military strategies

C . skills training for soldiers

Explanation:

Baron Friedrich von Steuben was a Prussian military officer, who went to Valley Forge on February 23, 1778. He contributed to the America by giving skills training for soldiers in different ways such as boosting confidence,  close-order drill, and discipline in the Continental Army.

Steuben also created a training manual for the Continental Army that helped them to fight in the war.

Hence, the correct answer is "C . skills training for soldiers".