We are asked to find the verb form of the adjective 'troublesome'.
- 'Troublesome' is an adjective that describes something causing trouble. The noun form of 'troublesome' would be 'trouble'.
- Option 1, 'trouble-creator', is a noun phrase but not the correct verb form.
- Option 2, 'comfortable', is an adjective and unrelated to 'troublesome'.
- Option 4, 'discomfort', is a noun and not the verb form.
- Option 3, 'trouble', is the verb form and best matches the given adjective.
Thus, the correct answer is option (3).