Trial and Error best describes the problem-solving approach to the concrete operational thinker because children during 7 to 12 years old think unsystematically for a solution.
Moreover, concrete operational thinkers uses several methods to solve a problem. When one method does not work, then another method is use until it satisfy the problem. This example defines trial and error method.
Answer: A - He called for reforms to try to help the USSR out of its economic trouble
B - He was general secretary of the Soviet Union
E - He made reforms that resulted in major social changes to the country.
Explanation:
Edge.
