The correct answer is option 2, Immune. HIV, which stands for Human Immunodeficiency Virus, primarily attacks the immune system of the body. The virus targets and attacks certain cells in the immune system called CD4 cells or T-helper cells. These cells play a crucial role in coordinating the body`s immune response to infections and diseases.
When HIV infects CD4 cells, it replicates inside them and gradually destroys them. As a result, the immune system becomes weakened and unable to effectively fight off infections and diseases. This makes people living with HIV more susceptible to various opportunistic infections and certain types of cancers.
It is important to note that HIV does not directly attack other systems of the body, such as the cardiovascular system (option 1), respiratory system (option 3), or reproductive system (option 4). However, the weakened immune system caused by HIV can indirectly affect these systems, making individuals more prone to illnesses and complications related to these systems.
Therefore, the primary system of the body attacked by HIV is the immune system.