1. Lila shares a house with two other people. She is a concert pianist and often practices at home. One roommate enjoys listening to her practice, but the other does not. For the roommate who enjoys listening to Lila play, this is an example of ; for the other roommate, it is an example of .'

a positive externality; a negative externality

Explanation:

answer; i believe the best and correct answer is stronger bonds between the nations of africa;

explanation:

allergens: overstimulate the nerve system

neurotics: attack nerve cells

mutagens: damage or otherwise alter dna sequence

generators: cause defects during growth and development  

carcinogens: cause unchecked cell growth

i hope you get the idea according to me these are the effects that happened.