Saliva has multiple benefits for our oral health, but option 2 stating that it increases RBCs in the body is incorrect. Saliva does not play a direct role in the production or regulation of red blood cells.

Option 1 correctly states that saliva facilitates swallowing by moistening food, making it easier to move down the throat. Option 3 is also correct in mentioning that saliva helps keep the mouth and teeth clean. Saliva contains enzymes that break down food particles and protect against tooth decay. Option 4 accurately explains that saliva aids in speech by facilitating the movements of the lips and tongue.

Therefore, the true answer is option 2 is not a benefit of saliva, as saliva does not increase the number of red blood cells in the body.