**Core Concept**
The HIV virus targets and infects CD4+ T lymphocytes, which play a crucial role in the immune system's response to infections. The virus uses its envelope glycoproteins to bind to the CD4 receptors on the surface of these cells.

**Why the Correct Answer is Right**
HIV has a high affinity for CD4+ T lymphocytes due to the presence of CD4 receptors on their surface. The virus's envelope glycoprotein, gp120, binds to the CD4 receptor, allowing the virus to fuse with the host cell membrane and release its genetic material. This interaction between gp120 and CD4 is essential for the virus to enter and infect the host cell. The CD4 receptor is present on the surface of macrophages and dendritic cells as well, but the affinity of HIV for these cells is lower compared to CD4+ T lymphocytes.

**Why Each Wrong Option is Incorrect**
**Option A:** While HIV also infects macrophages, the affinity of the virus for these cells is lower compared to CD4+ T lymphocytes.
**Option B:** HIV does not have a high affinity for B lymphocytes, which are primarily responsible for producing antibodies.
**Option C:** HIV does not have a high affinity for natural killer cells, which are a type of immune cell that plays a role in the innate immune response.

**Clinical Pearl / High-Yield Fact**
It's essential to note that HIV can also infect other cells, such as macrophages and dendritic cells, but the affinity of the virus for these cells is lower compared to CD4+ T lymphocytes. This is why CD4+ T lymphocytes are a critical target for HIV and are often used as a marker for HIV disease progression.

**Correct Answer: C. CD4+ T lymphocytes. CD4+ T lymphocytes.**