Explanation:

- Option 2: T Cells

- Correct Answer: The primary cells affected by HIV are T cells, specifically CD4+ T helper cells. HIV attacks and destroys these cells, which play a critical role in the immune system by coordinating the response to infections.

- Option 1: Neuron Cells

- Neuron cells, or nerve cells, are primarily involved in transmitting signals throughout the nervous system. HIV does not specifically target neuron cells, but it can lead to neurological complications indirectly.

- Option 3: Extracellular Matrix Cells

- The extracellular matrix is a network that provides structural support to cells but is not a specific target of HIV.

- Option 4: Contractile Cells

- Contractile cells are involved in muscle contraction, including heart and skeletal muscles. HIV does not specifically target these cells, although the infection and its complications can indirectly affect the heart.