The correct answer is C. Alexander wins the battle
Step-by-step explanation:
In this excerpt, the narrator explains there is a conflict between Alexander's troops and Dario's troops. Moreover, these leaders have different strategies, on one hand, Dario orders his troops to stay awake during the night "ordered his army to stand to throughout the night in readiness for a surprise attack", while Alexander decided his troops needed to rest. This implies next morning Alexander's troops will have all the energy for the battle and the alertness the author mentions in the last sentence "the alertness of one side and the fatigue of the other played at least some part in the outcome" will favor Alexander; therefore, this line suggests Alexander wins the battle.