The Footsteps

Lucas was at the library, poring over the latest mystery novel by his favorite author. Ever since he was little, Lucas had loved to read, and he was particularly fond of stories that were full of suspense and mystery. He finished reading the book and looked at his watch, realizing that it was nearly time for the library to close. When he walked up to the librarian's desk to return the book, she asked him if he liked reading it, and he replied that he had enjoyed it greatly. He then walked out of the library, zipping up his jacket to shield himself from the frosty wind, his head still full of thoughts about the book he had just read.
Lucas lived only a few blocks away from the library, so he decided to walk home. He turned into a deserted lane which was only lit by one lamppost. Suddenly, he thought he heard a noise behind him. When he turned, he saw nothing there. Shaking his head, Lucas kept walking. After a few more steps, he heard the noise again. It sounded like footsteps. His heart beating wildly, Lucas picked up his pace. The footsteps behind him picked up pace as well. Convinced that he was being followed, Lucas began to run. Suddenly, he tripped and fell. The footsteps reached him and stopped. Lucas peered up at the face looming over him. Then, a familiar voice asked him if he was hurt. It was Mr. Delfino, who Lucas regularly saw at the library. He explained that Lucas had left his wallet behind at the library and that he had been trying to catch up with Lucas to return it. Embarrassed, Lucas got back on his feet and thanked Mr. Delfino for returning his wallet, silently vowing never to read mystery novels at such late hours.
Which narrative technique does the author use to create an element of suspense?
A.
imagery
B.
foreshadowing
C.
pacing
D.
flashback

C. pacing