B. Older animals are usually surly and ill-tempered.- That can be a sentence in itself as well as the second part. Accordingly it is unwise to attempt to pet a grown raccoon. All the semicolon is doing is combining two sentences to make them one.
Number three is hopelessness
If you mean figurative language then
"air of night"
Usually conjunctions are not a good way to start a sentence; such as 'and' and 'but'...
