The purpose of expository writing is to inform, explain, describe, or define the author's subject to the reader.
You'd use this type of writing when you want to explain a certain term or idea to your readers, or just to give them an opportunity to learn something more about it, and for them to be informed/understand something they didn't prior to that.
That is a fragment.
This is just a dependent clause. This doesn't have a subject (it doesn't tell who specifically has received abundant praise)
Answer:
The reaction of the older European men about the killing of the elephant was that A. They agree with the narrator that it needed to be killed
Explanation:
The narrator killed the elephant to do what people were expecting him to do as a police officer, he says in the last lines " he shot the elephant because he didn't want to look like a fool", despite the fact that he hesitated about killing him before he did and he also mentions the respect he felt for majestic big animals like that one, older European men agreed that the animal needed to be killed because they considered that image matters and that was the action that a police officer was supposed to take.
I don't know if you have a specific word bank, but i would call this an "object-action" or "object-function" analogy. the object is the plankton, and plankton's action is to drift. the object is the bird, and birds fly.