单项选择题

It [sleepiness] filled my brain like a cloud. I was going, going...()

A. I was almost overcome by sleepiness and would doze off any moment.
B. I was trying hard to beat back sleepiness so that I could keep moving.
C. Due to sleepiness, I was not aware that I had lost my sense of direction.
D. Sleepiness clouded my mind and I was unable to see or hear clearly.