**Core Concept**
Zidovudine, a nucleoside reverse transcriptase inhibitor (NRTI), is a cornerstone in the treatment of HIV/AIDS. Its use is associated with several complications, primarily due to its mechanism of action and the effects of its metabolites on bone marrow.

**Why the Correct Answer is Right**
Zidovudine works by inhibiting the reverse transcriptase enzyme, which is essential for viral replication. However, this action also affects the host cell's ability to synthesize DNA, leading to myelosuppression. The primary complication of zidovudine therapy is bone marrow suppression, which manifests as anemia, neutropenia, and thrombocytopenia. These hematologic abnormalities occur due to the inhibition of DNA synthesis in bone marrow cells.

**Why Each Wrong Option is Incorrect**
**Option A:** Bone marrow suppression is the primary complication of zidovudine therapy, not gastrointestinal disturbances. While zidovudine can cause nausea, vomiting, and diarrhea, these are not the most significant complications associated with its use.
**Option B:** Lactic acidosis is a complication associated with nucleoside reverse transcriptase inhibitors, but it is more commonly seen with stavudine and didanosine. Zidovudine is less likely to cause lactic acidosis compared to other NRTIs.
**Option C:** Hepatotoxicity is not a common complication of zidovudine therapy. While zidovudine can cause elevations in liver enzymes, severe hepatotoxicity is rare and not a primary concern.

**Clinical Pearl / High-Yield Fact**
To remember the primary complication of zidovudine therapy, recall the phrase "Zidovudine: Zapping DNA, Zapping Bone Marrow."

**Correct Answer: A. Bone marrow suppression is the primary complication of zidovudine therapy, manifesting as anemia, neutropenia, and thrombocytopenia.**