What is the role of the digestive system?

The role of the digestive system primarily involves breaking down food into absorbable units. This process begins in the mouth, where mechanical digestion occurs as food is chewed and mixed with saliva. As food travels through the esophagus to the stomach, gastric juices further break it down chemically. The small intestine plays a crucial role in this process as well, as it is where most digestion and absorption of nutrients occur. The remaining undigested food then passes to the large intestine, where water and electrolytes are reabsorbed.

The absorption of nutrients is vital for providing the body with the energy and building blocks it needs to function. Overall, the primary purpose of the digestive system is to convert the food we eat into the nutrients our body needs, making option B the correct choice.

In contrast, the other options refer to functions of different body systems: circulating hormones pertains to the endocrine system, transporting oxygen to body tissues is a function of the respiratory and circulatory systems, and filtering blood relates to the renal system.