## Core Concept
Acute rejection of a renal transplant involves an immune response against the graft, leading to damage and potential loss of function. This process can be mediated by T cells (cellular immunity) or antibodies produced by B cells (humoral immunity). Histological examination is crucial for diagnosing acute rejection.

## Why the Correct Answer is Right
The correct answer, , typically shows characteristics such as:
- **Infiltration of lymphocytes** (particularly T cells) into the graft.
- **Interstitial inflammation** and **edema**.
- **Tubulitis**, which is inflammation of the renal tubules.
- **Endarteritis**, which is inflammation of the arterial walls within the graft.

These features are indicative of an acute cellular rejection process, which is a common cause of graft dysfunction in the early post-transplant period.

## Why Each Wrong Option is Incorrect
- **Option A:** This option might show changes related to chronic rejection or other forms of graft injury but does not specifically represent acute rejection.
- **Option B:** This could represent a different pathological process, such as a drug effect or a viral infection, rather than acute rejection.
- **Option D:** This option might be related to another type of rejection or a non-rejection cause of graft dysfunction.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **acute tubular necrosis (ATN)** and acute rejection are two distinct causes of early post-transplant renal dysfunction. While both can present with similar clinical features (e.g., rising serum creatinine), their histological features are distinct: ATN shows **tubular damage** without significant inflammation, whereas acute rejection shows **inflammation and immune cell infiltration**.

## Correct Answer Line
**Correct Answer: C.**