The largest and most consequential physical event on infrastructure to date was on Pacific Gas & Electric's (PG&E) Metcalf Substation (500 kilovolts [kV]) in California when it was attacked in April 2013 by snipers. Which of the following measures did PG&E NOT take to mitigate such events in the future?
A) Increasing security personnel
B) Installing bulletproof barriers
C) Relocating the substation
D) Enhancing cybersecurity