**Core Concept**
Benzathine penicillin is a long-acting, depot form of penicillin used to treat syphilis. It is administered via intramuscular injection to provide sustained therapeutic levels of penicillin in the body.

**Why the Correct Answer is Right**
Benzathine penicillin is the preferred treatment for early syphilis due to its high efficacy and convenience. The recommended dose of benzathine penicillin for early syphilis is 2.4 million units administered intramuscularly as a single dose. This dose is effective in treating the infection by inhibiting the growth of the bacteria *Treponema pallidum*, which causes syphilis. The benzathine moiety binds to the penicillin molecule, prolonging its action and allowing for less frequent dosing.

**Why Each Wrong Option is Incorrect**
**Option A:** 1.2 million units is an incorrect dose for early syphilis treatment.
**Option B:** 4.8 million units is excessive and may cause unnecessary side effects.
**Option C:** Oral penicillin is not effective for treating syphilis due to poor gastrointestinal absorption.

**Clinical Pearl / High-Yield Fact**
It is essential to note that benzathine penicillin is the only recommended treatment for syphilis during pregnancy, as it is safe and effective in preventing congenital syphilis.

**Correct Answer:** B. 2.4 million units.