Answer:
I think its D. temperature and dissolved oxygen
If an essay is order Chronologically, then it is more or less like steps. So we would want a(n) transitional phrase that sounds like it could fit into a step process. That would be "Afterward," This phrase is most likely to show up in a chronological essay than the others. If you look at the others they are all shadowing further elaboration on something.
The answer is afterward
What? are you trying to comment to someone?
D) is the only answer choice that does not make sense.