**Core Concept**
TXA2 (thromboxane A2) is a prostanoid synthesized in platelets from arachidonic acid through the cyclooxygenase (COX) pathway. It plays a crucial role in platelet aggregation and vasoconstriction. TXA2 has potent vasoconstrictive properties and promotes platelet adhesion and aggregation.

**Why the Correct Answer is Right**
TXA2 has pro-aggregatory properties, meaning it promotes platelet aggregation, rather than having anti-aggregatory reactivity. This is because TXA2 stimulates platelet activation and aggregation through its binding to the TP receptors on platelets. In contrast, anti-aggregatory agents, such as aspirin, inhibit platelet aggregation by blocking the production of TXA2.

**Why Each Wrong Option is Incorrect**
**Option A:** TXA2 is indeed formed in platelets, which are the primary site of its synthesis. Platelets contain the necessary enzymes and receptors for TXA2 production and action.
**Option B:** TXA2 is formed from PGG2/PGH2, which are intermediates in the arachidonic acid cascade. PGG2/PGH2 are converted to TXA2 by the enzyme thromboxane synthase.
**Option D:** Aspirin can indeed inhibit the production of TXA2 by irreversibly inhibiting the COX-1 enzyme, which is responsible for its synthesis.

**Clinical Pearl / High-Yield Fact**
TXA2 is a key mediator of platelet aggregation and vasoconstriction. Aspirin's ability to inhibit TXA2 production makes it a useful antiplatelet agent in the prevention and treatment of cardiovascular diseases.

✓ Correct Answer: C. It is having platelet anti aggregatory reactivity