Answer:
A. The essay is his homework
Explanation:
When people write an essay they typically do it for homework.
Despite the cold and how tired it must be from flying for so long, the waterfowl continues on its journey without faltering.
A journal that is unlikly to come across
Neither and nor are used together.
Either and or are used together.
B uses neither and or together, so that is wrong.
C uses either and nor together, so C is wrong.
D uses neither and or together, so D is wrong.
That leaves A.
A used neither and nor together, which is correct.
So the answer is A.