How many cases of AIDS have been diagnosed since 1981?

The correct answer reflects a significant statistic regarding the impact of AIDS since its first identification in the early 1980s. Since 1981, the cumulative number of AIDS diagnoses has surpassed 1.6 million in the United States alone. The selection of this choice indicates an understanding that the number of diagnosed cases is not only substantial but also highlights the serious nature of the epidemic.

The figure aligns with health reports and studies that estimate around 1,200,000 people are currently living with HIV in the U.S., with a significant portion having progressed to AIDS. Thus, the recognition of this larger scope emphasizes the long-term public health challenge AIDS has posed over several decades.

While the other options may seem plausible at first glance, they do not accurately represent the scale of the pandemic's impact in terms of diagnosed cases. The actual numbers in the context of health statistics underline the importance of ongoing awareness, education, and advocacy for prevention and treatment strategies in battling this disease.