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'.

[Q]: Question: Which of the following molecules has a simple covalent bond? 
 Options:  <1> C2. <2> N 2 <3> O 2 <4> O 3. <5> F 2
[A]: 5


[Q]: Question: The most common pancreatic cancer is: 
 Options:  <1> The intraductal mucinous papillary tumor. <2> Pancreatic neuroendocrine carcinoma. <3> The pancreatic cystadenocarcinoma. <4> The malignant insulinoma. <5> Ductal adenocarcinoma of the pancreas.
[A]: 5


[Q]: Question: In the respiratory chain: 
 Options:  <1> Ferrosulfurized proteins contain heme groups. <2> The heme groups are in carotenoids. <3> Cytochromes contain iron and sulfur groups. <4> Ubiquinones transport protons and electrons. <5> All transporters carry two electrons.
[A]:
4