Final answer:
HIV-1 is the variant of Human Immunodeficiency Virus causing the global AIDS epidemic, not HIV-2, which is concentrated in West Africa.
Step-by-step explanation:
HIV-1 is the type of Human Immunodeficiency Virus (HIV) causing the global AIDS epidemic. HIV-1 occurs in human populations worldwide and has led to millions of deaths since it was first identified in 1981. Unlike HIV-1, HIV-2 is primarily located in West Africa and is less transmissible, making it less prevalent worldwide. The HIV pandemic has been most devastating in sub-Saharan Africa, where a significant portion of the population is affected and access to treatment and prevention strategies is limited.