D. An activist bombs an automobile factory to protest corporate pollution.
Terrorism is, within the broadest sense, the employment of purposely indiscriminate violence as a method to make terror among lots of people; or worry to attain a monetary, political, non-secular or philosophic aim. It is not necessary that always involve people from another country or background.
Christopher Columbus (1451-1506) was an Italian explorer who sailed across the Atlantic Ocean in 1492, hoping to find a route to India (in order to trade for spices).