The above diagram represents stomach of ruminants. Identify A,B, C and D. What will happen if A will not function properly in ruminants?

When a person puts food in his mouth, then teeth cut it into small pieces, chew and grind it. The glands A in the mouth secrete a substance B which is mixed with the food by the tongue. The substance B contains an enzyme C which starts the digestion of food in the mouth. The slightly digested food from the mouth goes down a tube called oesophagus and subsequently passes through different organs and glands for the digestion process.

What is (i) gland A (ii) substance B, and (iii) enzyme C?