Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
Absorptive protists absorb food molecules across their cell membranes. This occurs by diffusion. These protists are important decomposers.


Question: Which process helps absorptive protists absorb food molecules across their cell membranes?
diffusion
Diffusion.