**Core Concept**
Granulomatous reactions are a type of chronic inflammatory response characterized by the formation of granulomas, which are aggregates of macrophages and other immune cells that attempt to wall off and eliminate foreign substances, such as parasites or their products. In the context of schistosomiasis, granulomatous reactions occur in response to the presence of ova or products of schistosomes at the sites of oviposition, leading to tissue damage and fibrosis.

**Why the Correct Answer is Right**
Schistosomiasis, caused by the parasitic flatworms Schistosoma mansoni, S. haematobium, and S. japonicum, leads to granulomatous reactions in the liver, intestines, and bladder. However, cardiac abnormalities are not a typical manifestation of granulomatous reactions caused by schistosomes. The primary sites of involvement in schistosomiasis are the liver and intestines, where the eggs of the parasite cause fibrosis and tissue damage. In contrast, S. haematobium infection can lead to bladder wall hyperplasia, which is a result of chronic inflammation and fibrosis.

**Why Each Wrong Option is Incorrect**
**Option A:** Bladder wall hyperplasia can occur in response to chronic inflammation and fibrosis caused by S. haematobium infection, making this option a possible clinical manifestation of granulomatous reactions.
**Option B:** Portal hypertension can occur as a result of liver fibrosis caused by schistosomiasis, making this option a possible clinical manifestation of granulomatous reactions.
**Option D:** Splenomegaly can occur in response to portal hypertension caused by liver fibrosis, making this option a possible clinical manifestation of granulomatous reactions.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the clinical manifestations of schistosomiasis depend on the species of the parasite and the site of oviposition. S. haematobium infection is primarily associated with urinary tract symptoms, while S. mansoni and S. japonicum infections are associated with gastrointestinal symptoms.

**✓ Correct Answer: C. Cardiac abnormalities**