**Core Concept**
Cryptorchidism, also known as undescended testis, is a condition where one or both testes fail to descend into the scrotum. Orchidopexy, or orchiopexy, is a surgical procedure to bring the undescended testis down into the scrotum. The goal of this surgery is to maximize fertility potential and reduce the risk of testicular cancer.

**Why the Correct Answer is Right**
The correct answer is related to the concept of "testicular descent." Testicular descent occurs between 28 and 35 weeks of gestation. If the testes do not descend, it can lead to impaired spermatogenesis and reduced fertility potential. Orchidopexy should be performed before the age of 1 year to maximize the chances of spontaneous testicular descent and to promote normal testicular development. This timing is also critical to minimize the risk of testicular cancer, which is higher in undescended testes.

**Why Each Wrong Option is Incorrect**
**Option A:** There is no specific age limit for orchidopexy after 1 year, but it is generally recommended to perform the surgery before the child reaches 1 year of age to maximize fertility potential.
**Option B:** The correct answer is not related to the age of 6 months, but rather to the age of 1 year.
**Option C:** There is no specific evidence to support a correlation between the age of 9 months and fertility potential in undescended testes.

**Clinical Pearl / High-Yield Fact**
It is essential to note that the American Academy of Pediatrics recommends that orchidopexy should be performed before the child reaches 1 year of age to maximize fertility potential and reduce the risk of testicular cancer.

**Correct Answer:** C. 1 year