Question: Indicate which of the following activities create a positive externality, a negative externality, or no externality at all:
a. During a live-theatre performance, an audience member's cellphone rings loudly.
b. You are given a flu shot.
c. You purchase and drink a soft drink during a break from class.
d. A local youth group cleans up trash along a two-kilometre stretch of highway.
e. A firm dumps chemical waste into a local stream.
f. The person down the hall in your residence plays a Britney Spears CD loudly while you are trying to sleep.