**Core Concept**
Post-mortem clots are a type of thrombus that forms after death, often in the veins or arteries of the body. This phenomenon is influenced by the coagulation cascade and the breakdown of the body's natural anticoagulant mechanisms after death.

**Why the Correct Answer is Right**
Post-mortem clots are characterized by their location, typically in the larger vessels, and their composition, which is rich in fibrin and platelets. The formation of these clots is facilitated by the release of tissue thromboplastin from damaged endothelial cells, which activates the coagulation cascade. This process is further enhanced by the absence of anticoagulant mechanisms, such as the inhibition of thrombin by antithrombin, after death.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because post-mortem clots are not typically associated with the presence of bacteria or infection.
**Option B:** This option is incorrect because post-mortem clots are not usually found in the microvasculature, but rather in larger vessels.
**Option C:** This option is incorrect because post-mortem clots do not typically exhibit the same organization or structure as living clots.

**Clinical Pearl / High-Yield Fact**
When interpreting post-mortem clots, it is essential to consider the timing of death and the potential for clot formation in living individuals with underlying coagulopathies or vascular disease.

**Correct Answer: B. They are found in larger vessels and are rich in fibrin and platelets.**