Final answer:
Laurens serves as an aide-de-camp to General Washington, Lafayette commands American troops, and Mulligan serves as an artillery officer. The correct option is a.
Step-by-step explanation:
During the Battle of Yorktown, Laurens, Lafayette, and Mulligan played crucial roles in supporting the American forces. Laurens served as an aide-de-camp to General Washington, providing valuable assistance in various capacities. Lafayette commanded American troops, contributing to the overall strategy and execution of the battle. Mulligan played a role as an artillery officer, overseeing the use of artillery in the American forces' military operations.
Thus the correct option is a.