**Core Concept**
A large hydrocele in an infant is an abnormal accumulation of serous fluid in the tunica vaginalis, a potential space surrounding the testis. The underlying principle is that the treatment should address the underlying cause, which may be related to the patent processus vaginalis, a communication between the abdominal cavity and the scrotum.

**Why the Correct Answer is Right**
The correct approach to treating a large hydrocele in an infant involves addressing the patent processus vaginalis, which allows fluid to pass from the abdominal cavity into the scrotum. This communication typically closes spontaneously by 1-2 years of age. However, if the hydrocele persists, surgical intervention may be necessary. The procedure of choice is herniotomy, which involves ligating the patent processus vaginalis to prevent further fluid accumulation.

**Why Each Wrong Option is Incorrect**
**Option A:** Manual compression or aspiration is not a recommended treatment for a large hydrocele in an infant, as it may not address the underlying cause and may lead to recurrence.
**Option B:** Conservative management with watchful waiting is not suitable for a large hydrocele in an infant, as it may cause discomfort and may lead to complications such as testicular torsion.
**Option C:** Orchiopexy is a surgical procedure used to correct undescended testes, not hydroceles.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that the treatment of a large hydrocele in an infant should be focused on addressing the underlying patent processus vaginalis, and herniotomy is the procedure of choice to prevent recurrence.

**Correct Answer:** D. Herniotomy.