The cleanest route to the answer is to look for the single agent that ticks all three boxes at once: bed-wetting, attention deficit, and persistent pain.
Tricyclic antidepressants are the only class that classically spans these conditions. Among the choices, imipramine is the prototype TCA and is the textbook drug for childhood nocturnal enuresis; it is also employed in ADHD and is a recognised treatment for chronic and neuropathic pain through its effect on monoamine reuptake and sodium channels.
The two SSRIs on the list, fluvoxamine and fluoxetine, treat depression and anxiety disorders but have no role in enuresis or analgesia. Bupropion helps with depression, smoking cessation and to some degree ADHD, yet it does not cover enuresis or chronic pain. Only imipramine satisfies every part of the stem.
\[\boxed{\text{Imipramine}}\]