Option (D.) Nitric oxide is not a component of saliva.
Components of human saliva -
- Saliva mainly consists of three types - Serous, Mucous and Mixed types which are secreted by different salivary glands.
- It is composed of water, mucus, proteins, mineral salts and amylase.
- Saliva consists of lysozyme which participates in the host non-immune defense against bacteria
- Defensins helps in protecting the mouth oral cavity from viruses which enters through the mouth.
- Defensins and lysozyme also maintains the steady state equilibrium of the oral cavity environment.
- The cyanide compound is also present in the saliva which regulates the urea content balance in the mouth.
Thus Option D. nitric oxide can't be present in saliva as all the other component are present in human saliva.
To learn more about human saliva, refer -
https://brainly.com/question/3312656
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