**Core Concept**
Excessive oxygen concentration in neonates can lead to a condition known as Retinopathy of Prematurity (ROP), a disease of the eye affecting prematurely-born babies generally having birth weight less than 1250 grams or gestational age of less than 31 weeks. This condition is characterized by abnormal growth of blood vessels in the retina.

**Why the Correct Answer is Right**
High concentrations of oxygen in neonates can lead to ROP due to the high reactivity of the premature retina. The normal development of retinal vessels is disturbed by excessive oxygen levels, causing a shift from normal angiogenesis to abnormal angiogenesis. This results in the formation of fragile, leaky blood vessels in the retina, which can lead to retinal detachment and vision loss. The exact mechanism involves the expression of vascular endothelial growth factor (VEGF), which promotes angiogenesis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while hypoxia can also cause ROP, it is not directly related to excessive oxygen concentration.
**Option B:** This option is incorrect because although oxygen toxicity is a known complication of high oxygen concentrations, it is not the primary cause of ROP in neonates.
**Option C:** This option is incorrect because while systemic hypoxia can cause a range of complications in neonates, it is not directly related to the development of ROP.

**Clinical Pearl / High-Yield Fact**
Neonates with a birth weight less than 1250 grams or gestational age of less than 31 weeks are at high risk for ROP, and should be closely monitored for signs of this condition.

**Correct Answer: C. Oxygen toxicity.**