Answer:
E. digestive system
Explanation:
Mollusks/Molluscs are invertebrates of the Kingdom Animalia. It is said to have the biggest population when it comes to the marine phylum.
It has an organ called the "radula" that is responsible for grinding food. This organ looks like a tongue. Its "crystalline style" is located in the middle part of its gut. It is responsible for secreting enzymes and it helps in extracellular digestions.
Clearly, the radula and crystalline style are both part of the mollusc's digestive system.
