Which of these is an example of a literal equation?

The incident command system (ics) is: a. most applicable to the management of complex incidents that extend over many hours or days. b. a military system used in domestic incidents to ensure command and control of federal resources. c. a standardized management tool for meeting the demands of small or large emergency or nonemergency situations. d. a relatively new approach created based on the lessons learned from hurricane harvey disaster operations.