To force the military of one country to work for the military of an opposing country

answer; the intervening variable;

answer; randomized controlled trials;

a family can go through many changes which would make it complex. having children can cause a change and increase the complexity. this would change the distribution of authority and management, as the older siblings will at some point be in charge of the younger ones, and discipline must be distributed when they get in trouble.

the secretary of defense is the principal defense policy advisor to the president. under the direction of the president, the secretary exercises authority, direction, and control over the department of defense.

as you did not provide any choices for me to choose from to give you a direct answer, this is the only information i can provide.