**Core Concept**
The endothelium plays a crucial role in maintaining vascular homeostasis, including regulation of coagulation. Endothelial cells produce various factors that promote or inhibit coagulation. **Procoagulant factors** are substances that promote blood clot formation.

**Why the Correct Answer is Right**
Endothelial cells produce **von Willebrand factor (vWF)**, a key procoagulant factor that helps initiate the coagulation cascade. vWF binds to **factor VIII**, stabilizing it and facilitating the formation of a **platelet plug**. Additionally, endothelial cells produce **tissue factor (TF)**, which triggers the extrinsic coagulation pathway.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not specified.
**Option B:** Incorrect because it is not specified.
**Option C:** Incorrect because it is not specified.

**Clinical Pearl / High-Yield Fact**
Remember that endothelial dysfunction can lead to an imbalance in procoagulant and anticoagulant factors, increasing the risk of **thrombosis**.

**Correct Answer:** D. von Willebrand factor and tissue factor.