One of the conclusions from the Iraq War was that US commanders found it difficult to respond to operational-level surprises, such as the fall of Mosul in 2004. Which of the following was a reason US commanders had this difficulty? A. US units remained too focused on the lower tactical fight throughout this period, allowing enemies to repeatedly achieve operational-level surprise. B. Constraints on force levels throughout the war meant that, aside from brief periods, the US had no operational reserve inside theater. C. US command and control systems at the time lacked the sophistication to quick respond to crisis over such a broad area