Answer:
Step-by-step explanation:
negative externality (NE)
positive externality (PE)
a. Overallocation of resources: NE
b. Tammy installs a very nice front garden, raising the property values of all the other houses on her block. PE
c. Market demand curves are too far to the left (too low). NE
d. Under allocation of resources. PE
e. Water pollution from factory forces neighbors to buy water purifiers. NE