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: The type of epidemiological study indicated to evaluate, in a population initially exempt from the health problem under study, the association between a risk factor and the onset of the disease is: 
 Options:  <1> Randomized clinical trial. <2> Quasi experimental. <3> Ecological studies <4> Cases and controls study. <5> Cohort study.

A: 3
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Q: Question: In eukaryotes, group II introns are in genes: 
 Options:  <1> Of rRNA. <2> From tRNA. <3> They encode proteins in the nucleus. <4> They encode proteins in mitochondria. <5> None is correct.

A: 4
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Q: Question: The recommended secondary prevention measure for the prevention of cervical cancer is: 
 Options:  <1> Vaccine against HPV. <2> Promote the use of condoms. <3> Substitute treatment of estrogen and progesterone in postmenopausal women. <4> Performing cervical cytology for women between 25 and 65 years <5> All are recommendations for secondary prevention.

A:
4
****