Which of the Following Findings Concerning Courthouse Shootings Is False

Which of the following findings concerning courthouse shootings is false?

A) The killing of a courthouse judge or police officer was the motive in 90 percent of these shootings.
B) About 40 percent of the shooters died, being killed either by security forces or by their own hand.
C) The majority of shootings occurred during the past 25 years.
D) About three-fourths of the firearms that were used were brought in by the shooter.