The sounding cataract haunted me like a passion: the tall rock, the mountain, and the deep and gloomy wood, their colours and their forms, were then to me an appetite;

a. the speaker's sadness at having lost his youthful passion
b. the speaker's inability to be thoughtful when he was younger
c. the speaker's fear when facing nature's great gloominess
d. the speaker's sensual response to nature in his younger days