Final answer:
Perinatal transmission from HIV-infected mothers taking antiretroviral therapy has the highest risk for HIV transmission.
Step-by-step explanation:
The highest risk for HIV transmission among the provided options is perinatal transmission from HIV-infected mothers taking antiretroviral therapy. This refers to the transmission of HIV from an HIV-infected mother to her child during pregnancy, childbirth, or breastfeeding. Without proper medical interventions like antiretroviral medications and cesarean delivery, the risk of transmission can be significant.