**Core Concept**
Acute humoral (also known as antibody-mediated) renal transplant rejection occurs when donor-specific antibodies bind to the graft, triggering a complement-mediated inflammatory response, leading to damage to the renal parenchyma. This type of rejection is often mediated by pre-existing or de novo donor-specific antibodies against human leukocyte antigens (HLA).

**Why the Correct Answer is Right**
The correct answer is characterized by the presence of donor-specific antibodies, activation of the complement system, and subsequent renal tissue damage. This process involves the binding of antibodies to the graft, which activates the complement cascade, leading to the formation of the membrane attack complex (MAC) and subsequent cell lysis. The renal biopsy in acute humoral rejection typically shows evidence of endothelial injury, interstitial inflammation, and thrombotic microangiopathy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because hyperacute rejection, while also antibody-mediated, occurs within minutes to hours after transplant and is characterized by immediate and severe graft dysfunction. Acute humoral rejection, on the other hand, typically occurs days to weeks after transplant.

**Option B:** This option is incorrect because the presence of donor-specific antibodies is a hallmark of acute humoral rejection. These antibodies can be detected using various assays, such as flow cytometry or enzyme-linked immunosorbent assay (ELISA).

**Option C:** This option is incorrect because the role of T cells in acute humoral rejection is minimal. Acute humoral rejection is primarily mediated by antibodies against HLA antigens on the graft.

**Option D:** This option is incorrect because the histopathological findings in acute humoral rejection typically include endothelial injury, interstitial inflammation, and thrombotic microangiopathy. While acute cellular rejection may show similar findings, the presence of donor-specific antibodies and activation of the complement system are key distinguishing features.

**Clinical Pearl / High-Yield Fact**
In the setting of acute humoral rejection, the use of intravenous immunoglobulin (IVIG) and plasmapheresis may be employed to remove circulating donor-specific antibodies and modulate the immune response.

**Correct Answer: A. Hyperacute rejection**