**Core Concept**
The Thomsen-Friedenreich (TF) phenomenon is a biological phenomenon where red blood cells exhibit agglutination in the presence of all blood group sera. This occurs due to the presence of a specific antigen on the surface of the red blood cells, which is normally hidden but becomes exposed under certain conditions.

**Why the Correct Answer is Right**
The TF antigen is a terminal galactose residue on the surface of red blood cells, which is normally masked by a sialic acid residue. However, when the sialic acid residue is removed, the galactose residue becomes exposed, leading to agglutination in the presence of all blood group sera. This is because the TF antigen is recognized by anti-TF antibodies present in the sera of individuals with different blood groups. The TF phenomenon is particularly relevant in the context of transfusion medicine, as it can lead to hemolysis of transfused blood.

**Why Each Wrong Option is Incorrect**
**Option A:** Red cells infection by CMV - This option is incorrect as the TF phenomenon is not related to CMV infection, but rather to the exposure of a specific antigen on the surface of red blood cells.

**Option C:** Hemolysis of transfused blood - While the TF phenomenon can lead to hemolysis of transfused blood, this option is incorrect as it is not a direct consequence of the phenomenon. The correct answer is related to the agglutination of red blood cells, not hemolysis.

**Option D:** Due to B antigen - This option is incorrect as the TF phenomenon is not related to the B antigen, but rather to the exposure of the TF antigen on the surface of red blood cells.

**Clinical Pearl / High-Yield Fact**
The TF phenomenon is an important consideration in transfusion medicine, as it can lead to hemolysis of transfused blood. However, it is worth noting that the TF antigen is normally masked by a sialic acid residue, and is only exposed under certain conditions.

**✓ Correct Answer: B. Red cell agglutination by all blood group sera.**