Answer:
from nervous to watchful to relaxed and content
Fred is frustrated with his e-mail provider because he didn't receive any e-mails today, due to a service outage.
The answer is option D: adverb.
<em>Sometimes </em>is an adverb of frequency, which indicates how often something happens. Adverbs of frequency are usually used for repeated or periodic activities, so they often go with the present simple tense. Other examples of adverbs of frequency are: <em>always</em>, <em>usually</em>, <em>often </em>and <em>never</em>.