Question #N391

The following text is from Bram Stoker’s 1897 novel Dracula. The narrator is being driven in a carriage through a remote region at night. The baying of the wolves sounded nearer and nearer, as though they were closing round on us from every side. I grew dreadfully afraid, and the horses shared my fear. The driver, however, was not in the least disturbed; he kept turning his head to left and right, but I could not see anything through the darkness. Which choice best maintains the parallel structure of the sentence?

Which choice best maintains the parallel structure of the sentence?
A. The driver, however, was not in the least disturbed, nor did he keep turning his head to left and right.
B. The driver, however, was not in the least disturbed, and kept turning his head to left and right.
C. The driver, however, was not in the least disturbed, and kept turning his head to left and right; he could not see anything through the darkness.
D. The driver, however, was not in the least disturbed, although he kept turning his head to left and right.