From the pH point of view, why is cleaning the mouth after meals useful for teeth?

Correct answer: It removes acid-forming residues and prevents pH from falling

The governing idea is that mouth bacteria can metabolise food residues, especially sugars, and release acids. These acids lower the oral pH; when the pH remains low, tooth enamel can lose minerals and decay becomes more likely. Cleaning or rinsing removes residues and reduces acid production, helping the pH move away from the harmful acidic range. It does not dissolve enamel or increase acidity, so option A is correct.