Digestion begins when salivary gland secretion enters what?

Mouth

Explanation:

Digestion is the breakdown of food into small pieces that the body can absorb and use. Similarly, the process of digestion begins in the mouth by chewing (mastication). Thus, secretion of the saliva by the salivary gland dissolves some the chewed food and facilitates its passage through the digestive tract.

the missing space is phylum