The first enzyme that acts on food in the digestive system
(a) Pepsin
(b) Trypsin
(c) Chymotrypsin
(d) Amylase

Hint: It very commonly knows that the process of digestion of food begins in the mouth. The enzyme is the constituent of saliva and acts on the carbohydrate in the mouth.

Complete answer:
The mouth is also called the buccal cavity, humans are holozoic organisms which means they ingest their food for nutrition. When the good enters the mouth the buccal cavity masticates the food (chewing) and when it is soft and lubricated enough the food is swallowed. In the mouth, the teeth, tongue, and saliva masticate the food and mix it and break it thoroughly into smaller pieces. The saliva helps to make the food adhere together and makes it a bolus. The saliva contains electrolytes like $Na^{+}$, $K^{+}$, $Cl^{-}$, $HCO^{-}$ and Salivary amylase. The digestion begins in the mouth, with the hydrolytic action of salivary amylase as it breaks down carbohydrates. It is studied that about 30% of the total starch in the food is hydrolyzed in the mouth. The pH of the mouth is about 6.8 which is the optimal pH for the functioning of this enzyme. The starch in the food which is a polysaccharide is broken down into maltose which is a disaccharide. Later in the intestines, this maltose is further broken down into glucose by the enzyme maltase.

So, the correct answer is ‘Amylase’.

Note:
The saliva also contains lysozyme. This works to kill bacteria present on or in the food which may be able to cause diseases. In the stomach, the pH reaches about 1 due to the HCL secreted by the stomach. This also works to kill bacteria.