Answer: The answer would be “difficult”.
Explanation: An adjective is a word that describes something. The word “difficult” describes the problem.
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.
What do you mean, you mean know?
A claim is something that can be defended with evidence while an opinion is just what you believe and does not require any evidence