You have four reasons for saying "no." Two of them are very strong reasons, one has a tiny loophole and one is very weak. In your message you should: (Points: 5)

include all four reasons.
omit the very weak reason and use the other three.
use only the two strong reasons.
give only the strongest reason.

Please understand that no one here will do your work for you. Please post what you think.

I am sorry this is my first time on here and do not know but i think it is C but is not sure

I agree with C.

In this situation, it would be most effective to include all four reasons for saying "no." This approach ensures transparency and provides a comprehensive explanation. By including all the reasons, you address any potential concerns or doubts the recipient may have. Moreover, it demonstrates that you have carefully considered the decision from multiple angles and are providing them with a fair assessment.