Answer: [B]: " Halcion™ " ; {generic name: "triazolam".}.
_____
Explanation: We are asked:
"Which of the following is a sleeping pill?" ;
And we are given 4 (four) answer choices.
Let's go through each of the 4 (four) answer choices presented:
_____
Choice: [A]: sumatriptan {brand name: " Imitrex™ " } ;
→ is one of the "triptans" that is exclusively used to treat "migraine headaches"—not "sleep".
_____
Choice: [B]: triazolam {brand name: " Halcion™ "} ;
→ is a "sleeping pill" that is prescribed only for "sleep problems" and/or to "induce sleep"—so this answer—at this point—may be correct!
_____
Let's continue with the remaining answer choices:
Choice: [C]: phenytoin {brand name: "Dilantin™ " } ;
→ is officially used to treat "epilepsy/other seizure disorders"—
as well as "off-label" medication for neuropathy, anxiety disorders; certain types of "pain"; and neuropsychiatric conditions—is not a "sleeping" medication.
_____
Choice: [D]: ondansetron {brand name: "Zofran™} ;
→ is an "anti-emetic" ['anti-nausea medication']/used to prevent nausea/vomiting— [and is Not a "sleeping" medication].
_____
So; our correct answer is:
Answer Choice: [B]: " Halcion™ " ; {generic name: "triazolam".}.
Hope this answer/explanation is helpful to you!
Best wishes!
_____