What are the three main components of blood?

The question asks to select three components that blood is made up of.

Blood is composed of several key components:

• Red Blood Cells (Erythrocytes): These cells carry oxygen from the lungs to the rest of the body and carbon dioxide back to the lungs.
• White Blood Cells (Leukocytes): These cells are part of the immune system and help fight infections and other diseases.
• Platelets (Thrombocytes): These are small, irregular-shaped cell fragments that play a crucial role in blood clotting to stop bleeding.
• Plasma: This is the liquid portion of blood, which carries blood cells, proteins, nutrients, hormones, and waste products throughout the body.

From the given options:

• Red Blood Cells are a primary component.
• Platelets are a primary component.
• White Blood Cells are a primary component.
• "Neutral Cells" is not a standard primary component of blood. While neutrophils are a type of white blood cell, "Neutral Cells" is not a general category for blood components.

Therefore, the three components blood is made up of are Red Blood Cells, Platelets, and White Blood Cells.

The final answer is $\boxed{\text{Red Blood Cells, Platelets, White Blood Cells}}$