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 medications is an anti CD20 monoclonal antibody used in the treatment of rheumatoid arthritis?
Options: <1> Alemtuzumab <2> Muromunab. <3> Abalizumab <4> Rituximab <5> Visilizumab.
[A]: 4

[Q]: Question: As an immunoanalytical technique, flow cytometry is mainly based on the detection of signals:
Options: <1> Chemiluminescent <2> Fluorescent <3> Bioluminescent <4> Piezoelectric. <5> Magnetic
[A]: 2

[Q]: Question: The degenerative neurological disorder that occurs as a result of degeneration and loss of nigrostriatal dopaminergic neurons is called:
Options: <1> Phenylketonuria <2> Transmissible spongiform encephalopathy or TSE. <3> Multiple sclerosis. <4> Huntington's disease <5> Parkinson's disease
[A]:
5