Final answer:
The incidence proportion in question refers to the newly diagnosed cases of breast cancer in the population of females screened, indicating option a as the correct answer.
Step-by-step explanation:
The incidence proportion in the context of the breast cancer screening program that screened 8000 females and discovered 35 females previously diagnosed with breast cancer, along with 20 females with no previous history of breast cancer diagnosed as a result of screening, would reflect newly diagnosed cases of breast cancer in this population of females. More specifically, the answer is option a: A newly diagnosed case of breast cancer in this population of females. The incidence proportion is a measure of new cases and does not include individuals who were already diagnosed in the past.
Routine cancer screening, such as mammograms for breast cancer, aim to detect cancer in asymptomatic people. This can lead to earlier treatment and potential cure. The incidence proportion is useful for understanding the new cases of a disease within a specified time frame for a given population.