Given a scientific question, generate a correct answer to it.

Ex Input:
Which process helps absorptive protists absorb food molecules across their cell membranes?

Ex Output:
diffusion

Ex Input:
What amazing machines smash particles that are smaller than atoms into each other head-on?

Ex Output:
particle accelerators

Ex Input:
Because it damages hair cells, what is the most cause of hearing loss in adults?

Ex Output:
exposure to noise