**Core Concept**
Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI) used in the treatment of HIV-1 infection. NNRTIs bind to the reverse transcriptase enzyme, disrupting its function and preventing viral replication.

**Why the Correct Answer is Right**
Efavirenz acts by binding to the reverse transcriptase enzyme at a site distinct from the substrate binding site, thereby altering the enzyme's conformation and inhibiting its activity. This leads to a decrease in viral replication and an increase in CD4+ T-cell count. Efavirenz is a potent inhibitor of HIV-1 replication, with a high genetic barrier to resistance and a long half-life, allowing for once-daily dosing.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect, as efavirenz does not act by inhibiting viral protease.
**Option B:** Incorrect, as efavirenz does not act by interfering with viral entry into host cells.
**Option C:** Incorrect, as efavirenz does not act by inhibiting viral integrase.

**Clinical Pearl / High-Yield Fact**
Efavirenz is known to cause central nervous system (CNS) side effects, including dizziness, insomnia, and vivid dreams, due to its ability to cross the blood-brain barrier. It is essential to counsel patients about these potential side effects before initiating therapy.

**Correct Answer:** B. Non-competitive inhibition of reverse transcriptase enzyme.