<span>"an enormous ornamental bat", because this is a humorous mental image, and
"as the atmospheric conditions demanded", because this is saying that the atmosphere and weather could make it necessary for someone to look a certain way (that's what is meant by putting on airs) rather than to actually stay dry or warm.</span>
Sentence provides commentary information for elaboration of a concrete detail.
D) It was a good idea to wear short sleeves and a light jacket that could be taken off easily in the afternoon.
The concrete detail:
short sleeves and a light jacket
The commentary information for elaboration of the concrete detail:
that could be taken off easily in the afternoon.
The Letter b might be right
