Fact 1: Mollusks are a major food source for other organisms, including humans.

Fact 2: Mollusks are invertebrates and are no exception.

Given the two facts above, answer the question "What is a major food source for other organisms, including humans?" with the following options: 
- gastropod shells
 - orchids
 - invertebrates
 - swamp vegetation
 - Most plants
 - insects
 - barnacles
 - animals


 

   invertebrates      