**Core Concept**
Undescended testes, also known as cryptorchidism, is a condition where one or both testicles do not descend into the scrotum. Orchidopexy, also known as orchiopexy, is a surgical procedure that involves bringing the undescended testis into the scrotum and anchoring it in place. The optimal age for performing orchidopexy is crucial to prevent potential complications and preserve fertility.

**Why the Correct Answer is Right**
The American Academy of Pediatrics recommends performing orchidopexy by 12-18 months of age. This is because undescended testes have a higher risk of testicular cancer, infertility, and testicular torsion if left untreated. The procedure is typically performed after 6 months of age to allow the testis to fully develop and to minimize the risk of complications during surgery. Early intervention also helps to prevent psychological and social issues associated with undescended testes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it is too early for orchidopexy. The testis may not have fully developed, and the procedure may be more challenging.
**Option B:** This option is incorrect as it is too late. The risk of testicular cancer and infertility increases with age, and the procedure becomes more complicated.
**Option C:** This option is incorrect as it is not a specific age and does not provide a clear guideline for performing orchidopexy.

**Clinical Pearl / High-Yield Fact**
It's essential for pediatricians and surgeons to discuss the risks and benefits of orchidopexy with parents and caregivers to make informed decisions about the optimal age for the procedure.

**Correct Answer:** C.