Question21)which of the following was not an effect of the bolshevik revolution a. all land banks mines and factories came under state control. b. the tsar and his family were executed c. russia withdrew from world war i. d. trostsky emerged as the dictator of the soviet union

from my knowledge I am confident to say it's A

Explanation:

my reason the Tsar was executed, they did withdrew from ww1 after the October revelation in 1917 and trostsky did emerge as the dictator of the Soviet union after the revolution

option d is correct. corroborated sources of historical evidence   is necessary to validate a claim about an event in history.

historians tend to use written sources, but audio and visual materials as well as artifacts are important objects that supply information to modern historians.

historical sources are usually divided into two categories: primary and secondary sources. depending on the historian's intent, some sources shift their designation. determining what type of sources toimplement, and the level of credibility and reliability of those sources, is a significant step in critical thinking for the historian.

explanation:

b. parliament was weaker than the monarchy.