**Core Concept**
Dicumarol is a vitamin K antagonist that inhibits the production of vitamin K-dependent clotting factors in the liver. In dicumarol overdose, the anticoagulant effect is enhanced, leading to an increased risk of bleeding.

**Why the Correct Answer is Right**
In dicumarol overdose, the correct approach is to administer **vitamin K** to reverse the anticoagulant effect. Vitamin K acts as a cofactor for the gamma-carboxylase enzyme, which is necessary for the activation of vitamin K-dependent clotting factors. By administering vitamin K, the production of these clotting factors is restored, thereby reversing the anticoagulant effect.

**Why Each Wrong Option is Incorrect**
**Option A:** Fresh frozen plasma (FFP) is not the first-line treatment for dicumarol overdose. While FFP can contain clotting factors, it is not a reliable or long-term solution, as the anticoagulant effect may recur.
**Option B:** Protamine is used to reverse heparin anticoagulation, not dicumarol. Protamine binds to heparin, forming a stable complex that is quickly excreted, thereby reversing the anticoagulant effect.
**Option C:** Transcarinic acid is an antifibrinolytic agent that inhibits the conversion of plasminogen to plasmin. It is used to prevent excessive bleeding in patients with trauma or surgery, but it is not indicated in dicumarol overdose.

**Clinical Pearl / High-Yield Fact**
In patients with dicumarol overdose, it's essential to monitor the international normalized ratio (INR) regularly and adjust treatment accordingly. Vitamin K administration should be continued until the INR returns to a safe range.

**Correct Answer:** C.