Fill in the blank with the most appropriate word.

This is one of the matters that ______ me the most.

disturbs

This is one of the matters that disturb me the most.

Explanation:

• Is disturbed: This doesn't fit because the subject "one of the matters" is plural, so the correct verb form should be plural as well.

• Disturbs: This is the correct form. "Disturbs" is the present tense verb form that agrees with the plural subject "one of the matters."

• Are disturbing: This doesn't fit because "are" is used with plural subjects, and "one of the matters" is singular.

• Has disturb: This is not grammatically correct. The correct form is "has disturbed" if you were using a singular subject.