This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Glycoprotein which is Lubricant & Protective 
Select and explain. 
A. Mucin, B. Immunoglobulin, C. Ovalbumin, D. None of these
A: Mucin
Answer: A: Mucin 
Explanation: Answer- A. Mucin* glycoproteins found in the body is mucins, which are secreted in the mucus of the respiratory and digestive tracts. The sugars when attached to mucins give them considerable water-holding capacity and also make them resistant to proteolysis by digestive enzymes.* O-Linked Glycans: * Mucins, which are found extensively in salivary secretions, contain many sho O-linked glycans. * Increase the viscosity of the fluids