In the last few decades, executive orders a. have become focused almost exclusively on emergency wartime measures rather than on domestic policy matters. b. have become routine instruments of presidential governance rather than emergency wartime measures. c. have ended entirely due to a series of Supreme Court decisions outlawing most forms of unilateral presidential action. d. have become increasingly rare due to the limitations Congress has imposed on unilateral presidential action.

Have become routine instruments of presidential governance rather than emergency wartime measures.

Explanation:

An Eecutive order is commonly defined as formal device, issued by the President mainly to control the workings of the executive branch by leading or directing the agencies that is made up of it. The president can exercise supervision and direct the agency. Usually not binding, not mentioned in the Constitution, and only function in a discretionary way.

Limitations includes that even when president can guide the discretion of agencies under his control, the president cannot legislate, cannot change appropriations, and cannot abrogate due process by determining the outcome of an adjudication.