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'.

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.
2

Question: Clostridium perfringens can cause various infections, including:
Options: <1> The anthrax. <2> Pseudomembranous colitis. <3> The gas gangrene. <4> Tetanus <5> The syndrome of scalded skin.
3

Question: Regarding the definition of chronic kidney disease, one is INCORRECT:
Options: <1> It requires persistent presence of structural or functional alterations of the kidney for at least 2 months. <2> It includes alterations in urine as proteinuria, independently of the glomerular filtration rate (GFR). <3> It includes a lower GFR of 60 ml / min / 1.73m2 of body surface regardless of the presence or absence of other markers of kidney damage. <4> It is classified into 5 stages according to the TFG. <5> The preparation for renal replacement therapy should be done in stage 4.
1