###INSTRUCTION: Fix grammaticality in this sentence: The collective idea of HIV/AIDS transmission is they contract it like their clients, whereas it is transmitted mostly by the sexual relations between partner.
###RESPONSE: 
The collective idea of HIV/AIDS transmission is that they contract it from their clients, whereas it is transmitted mostly by the sexual relations between partners.
The collective idea of HIV/Aids transmission is that they contract it like their clients; whereas, it is transmitted mainly through the sexual relations between a partner.