**Core Concept:** Renal transplant is a surgical procedure where a healthy kidney from a donor is transplanted into a patient with end-stage renal disease to restore renal functions. Recovery of renal functions after transplant is influenced by various factors like immune response, medication, and graft quality.

**Why the Correct Answer is Right:**
Recovery of renal functions after renal transplant usually takes time due to the immune system response against the grafted organ. The process involves an initial period of acute rejection followed by a gradual recovery period. Over time, the immune system learns to tolerate the new kidney, leading to a stable and functional renal graft.

**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because the recovery of renal functions occurs over time due to immune system response and not immediately.
B. This option is wrong as the recovery process involves an immune system response and gradual adjustment, not a sudden recovery.
C. While the recovery process includes immune system adjustment, this option is incorrect as it does not accurately describe the typical duration of the process.
D. This option is incorrect as it does not accurately describe the immune system response and the duration of recovery process.

**Clinical Pearl / High-Yield Fact:**
The recovery of renal functions after renal transplant usually takes around 3-6 months for acute rejection to subside and 1-2 years for the graft to reach a stable functional state. This highlights the importance of appropriate immunosuppressive therapy, monitoring, and follow-ups during this process.

**Correct Answer:** D. 3-6 months for acute rejection to subside and 1-2 years for the graft to reach a stable functional state.