**Core Concept**
The prophylactic care of newborn eyes involves the application of silver nitrate (AgNO3) eye drops to prevent gonococcal ophthalmia neonatorum, a serious infection that can cause blindness.

**Why the Correct Answer is Right**
Silver nitrate eye drops are effective against gonococcal ophthalmia neonatorum because they rapidly kill Neisseria gonorrhoeae, the causative organism. This is achieved through the antimicrobial properties of silver ions, which disrupt bacterial cell membranes and inhibit DNA replication. The application of AgNO3 eye drops is a standard public health measure to prevent neonatal blindness.

**Why Each Wrong Option is Incorrect**
**Option B:** Antibiotics are not used as a prophylactic measure for newborn eye care, as they may not be effective against gonococcal ophthalmia neonatorum and can promote antibiotic resistance.
**Option C:** Normal saline is not a suitable substitute for silver nitrate, as it does not have antimicrobial properties and would not prevent gonococcal ophthalmia neonatorum.
**Option D:** Crede's method involves the application of silver nitrate eye drops, but it is not the correct answer as it is not a standalone option. Crede's method is a specific technique that involves the instillation of silver nitrate eye drops after delivery.

**Clinical Pearl / High-Yield Fact**
The World Health Organization recommends the use of silver nitrate eye drops as a prophylactic measure to prevent gonococcal ophthalmia neonatorum in newborns.

**Correct Answer:**
✓ Correct Answer: A. AgNO3 eye drop