People told that a chemical in the air is projected to kill 10 out of every 10 million people feel more frightened than if told the fatality risk is 0.000001. This best illustrates the importance of

framing

Explanation:

In the field of social sciences, 'framing' may be defined as the set of theoretical perspectives and concepts on how a person, group of people or societies organize, and perceive and also communicate about the reality. It can manifest in interpersonal skills or in thoughts.

In the context, people would be more frightened when they were told that some chemical that have escaped to the air can kill 10 people out of 10 million than when they were told that the fatality risk of being killed by the chemical is 0.000001.

This best illustrates the importance of "framing".