Given a fact, create a question that can be answered using the fact. Construct the question such that it is unambiguous, has a unique answer and the answer can be given using the fact.

Fact: when light enters the eye through the pupil , that light falls on the retina
A retina may be illuminated by?

Fact: a squid produces thrust by pushing water out of its body
When a squid moves forward, water is?

Fact: objects made of glass cause refraction of light

glass crystals will cause light to?