A state epidemiologist is reviewing surveillance data for pertussis (Bordetella pertussis infection) across a region. The reported incidence increased from 4 cases per 100,000 population in 2018 to 7 cases per 100,000 in 2023. During this 5-year period, the state implemented mandatory PCR-based pertussis testing in all primary care clinics and emergency departments, whereas previous surveillance relied on clinical diagnosis and culture. Additionally, a public awareness campaign was launched after a school outbreak in 2020. The state's overall population remained stable at 5.2 million. Healthcare providers report more frequent testing for prolonged cough in both vaccinated and unvaccinated individuals. Which of the following best explains the observed increase in reported pertussis incidence?

1. A)True increase in pertussis incidence due to waning immunity from acellular vaccine formulations
2. B)Detection bias resulting from improved diagnostic testing and increased case identificationGABARITO
3. C)Selection bias introduced by preferential testing of symptomatic patients in outpatient settings
4. D)Confounding by increased migration of unvaccinated populations into the state
5. E)Survivor bias leading to improved ascertainment of mild cases previously unreported