Answer: b. Two reflecting pools with waterfalls were built in the footprints of the World Trade Center buildings.
Step-by-step explanation:
Personification refers to giving a inanimate object or an animal the characteristics of a human being such that describing it becomes easier.
By stating that the World Trade Centre had footprints, the sentence is giving the two buildings a human characteristic even though buildings cannot have footprints but by using the word, the reader is able to discern that the pools were built on the area where the World Trade Centre buildings once stood.