What does the empty ones mean (definition)

What triggered the surge of conservative governments in central europe at the end of world war i? a. the disintegration of european families in the wake of urbanization. b. a worldwide revolutionary upsurge. c. the revival of the austrian-hungarian and ottoman empires. d. the british suppression of the indian nationalist movement. e. the killing of the tsar during the russian revolution?

What principle did president truman invoke in sending u.s. troops into south korea without first asking congress to declare war?

Ascientist performs an experiment where she measures the mass of a piece of metal, pours acid onto the metal, washes the metal, and then re-measures the mass of the metal. the scientist repeats the experiment several times, each time increasing the amount of acid used. the dependent variable in the experiment is the: initial mass of the metal final mass of the metal amount of acid used washing the metal