The correct option is Serum.
Explanation
Blood is composed of a fluid matrix known as plasma and formed elements (erythrocytes, leukocytes, and thrombocytes). Plasma constitutes approximately 55% of blood volume and contains water, proteins (fibrinogen, globulins, albumins), minerals, and clotting factors required for coagulation.
Option Analysis:
- Serum is Correct: Serum is the fluid that remains after blood has clotted. It is essentially blood plasma minus the clotting factors (such as fibrinogen). Because the clotting factors are removed or used up during the coagulation process, serum does not clot.
- Lymph is Incorrect: Lymph is a colorless fluid found within the lymphatic vessels. It is chemically similar to plasma but contains lower protein concentration and lacks red blood cells. It facilitates the exchange of nutrients and gases between blood and cells.
- Plasma is Incorrect: Plasma is the liquid component of whole blood that retains all clotting factors. It is the medium in which blood cells are suspended.
- Chyle is Incorrect: Chyle is a milky bodily fluid consisting of lymph and emulsified fats (free fatty acids). It is formed in the small intestine during digestion and absorbed by lacteals.
Key Takeaway:
The primary difference between plasma and serum is the presence of fibrinogen and other coagulation proteins. The relationship is defined as: Serum = Plasma - Clotting Factors.