The correct answer is option 3 - Pancreas. The pancreas is a gland located in the abdomen, behind the stomach. It plays a crucial role in the digestive system by secreting enzymes that help break down proteins, carbohydrates, and fats in the food we eat. These digestive enzymes are released into the small intestine, where they aid in the process of digestion.

Option 1 - Large intestine: The large intestine, also known as the colon, primarily absorbs water from the remaining undigested food material. It does not secrete any digestive enzymes.

Option 2 - Liver: The liver is the largest internal organ in the human body, and while it does have many important functions, including the production of bile, which helps in the digestion of fats, it does not directly secrete digestive enzymes.

Option 4 - Spleen: The spleen is an organ involved in the immune system and the filtration of blood. It is not directly involved in the secretion of digestive enzymes.

Therefore, the correct answer is option 3 - Pancreas, as it is the gland responsible for secreting digestive enzymes in the human body.