**Core Concept**
Acute phase reactants are proteins whose plasma concentrations increase or decrease in response to inflammation, infection, or tissue damage. These proteins play a crucial role in the body's response to stress and injury, helping to modulate the inflammatory response and facilitate recovery.

**Why the Correct Answer is Right**
During inflammation, the liver produces and releases acute phase reactants into the bloodstream. Examples of acute phase reactants include C-reactive protein (CRP), serum amyloid A (SAA), and fibrinogen. These proteins help to modulate the inflammatory response by inhibiting the production of pro-inflammatory cytokines and promoting the production of anti-inflammatory cytokines. In contrast, lipoproteins are not typically considered acute phase reactants, as their plasma concentrations do not change significantly in response to inflammation.

**Why Each Wrong Option is Incorrect**
* **Option A:** C-reactive protein (CRP) is a well-known acute phase reactant, whose plasma concentration increases in response to inflammation.
* **Option B:** Serum amyloid A (SAA) is another acute phase reactant, whose plasma concentration increases in response to inflammation, particularly in response to bacterial infections.
* **Option D:** Fibrinogen is also an acute phase reactant, whose plasma concentration increases in response to inflammation, helping to facilitate blood clotting and tissue repair.

**Clinical Pearl / High-Yield Fact**
Fibrinogen is an acute phase reactant that serves as a precursor to fibrin, which forms the basis of blood clots. An elevated plasma concentration of fibrinogen is often seen in patients with chronic inflammation, infection, or malignancy.

**Correct Answer: D. Lipoproteins are not typically considered acute phase reactants, as their plasma concentrations do not change significantly in response to inflammation.