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: In the activation of the serum complement, the assembly of the Membrane Attack Complex begins with: 
 Options:  <1> C9 <2> C5b. <3> C3a. <4> C6 <5> C8.
[A]: 2


[Q]: Question: They incorporate sterols to their plasma membrane: 
 Options:  <1> Mycobacterium tuberculosis. <2> Micrococcus luteus. <3> Mycoplasma pneumoniae <4> Chlamydia trachomatis. <5> Rickettsia prowazekii.
[A]: 3


[Q]: Question: What favors the appearance of atherosclerotic plaques? 
 Options:  <1> Stress. <2> Asthma. <3> Angina of the chest. <4> Cannabis <5> Physical exercise.
[A]:
1