Answer:
 PART A: I don't know exactly what you read in your lesson, but from what I can tell, location a on the west coast of South America would be the most likely to experience a tsunami. 
PART B: Because it is chosen as the most likely place to experience a tsunami due to its proximity to the tectonic plate boundaries in the Pacific Ocean. Earthquakes, which can trigger tsunamis, are more frequent in these areas.
Step-by-step explanation: