In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.

Let me give you an example: Question: A 13-year-old girl is operated on due to Hirschsprung illness at 3 months of age. Which of the following tumors is more likely to be present? 
 Options: <1> Abdominal neuroblastoma <2> Wilms tumor <3> Mesoblastic nephroma <4> Familial thyroid medullary carcinoma.
The answer to this example can be: 2
Here is why: The answer to the given question should be a tumor, therefore Wilms tumor is the correct answer for the given question.

OK. solve this:
Question: Which of the following hydrides has the highest normal boiling point? 
 Options:  <1> SiH4. <2> CH4 <3> HCl. <4> PH3. <5> HF
Answer:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
5