**Core Concept**
Disseminated Intravascular Coagulation (D.I.C.) is a complex clinical disorder characterized by the systemic activation of coagulation pathways, leading to the formation of microthrombi in small blood vessels. This results in a consumptive coagulopathy, where both clotting factors and platelets are depleted, increasing the risk of bleeding and thrombosis.

**Why the Correct Answer is Right**
D.I.C. is a clinical condition where there is an imbalance between pro-coagulant and anti-coagulant mechanisms, leading to the activation of the extrinsic pathway of coagulation. This results in the formation of fibrin clots, which can occlude small blood vessels and lead to tissue ischemia. The coagulation cascade is initiated by the release of tissue factor, which activates factor VII and subsequent factors in the coagulation pathway.

**Why Each Wrong Option is Incorrect**
* **Option A:** Fibrinogen is a key component in the formation of fibrin clots and is indeed seen in D.I.C. Therefore, it is not the correct answer.
* **Option B:** D-dimer is a degradation product of cross-linked fibrin and is a sensitive marker for D.I.C. A positive D-dimer test is commonly used to diagnose D.I.C. Therefore, it is not the correct answer.
* **Option C:** This option is blank and cannot be evaluated.

**Clinical Pearl / High-Yield Fact**
In D.I.C., the coagulation cascade is activated, leading to the depletion of clotting factors and platelets. This can result in a hemorrhagic diathesis, characterized by bleeding from multiple sites, including mucous membranes, skin, and internal organs.

**Correct Answer:** D.