Sentence Correction

The science of economics, which for four decades was dominated by Keynesians, who at first stressed the government’s role in stimulating the economy, but who were ultimately led away from solutions based on government intervention.
(A) economics, which for four decades was
(B) economics that was to be
(C) economics, one which has, for four decades, been
(D) economics is one that for four decades has been
(E) economics, for four decades, is one that was

OA is E



The speculative fever of the Roaring Twenties infected rich and poor alike; vast quantities of people were dangerously overextended, credit was absurdly easy to obtain, and most brokerage houses required only ten percent cash for stocks bought on “margin.”
(A) rich and poor alike; vast quantities of people were dangerously overextended
(B) both rich and poor alike; large amounts of people dangerously overextended themselves
(C) rich and poor alike; great numbers of people were dangerously overextended
(D) both rich and poor alike; vast amounts of people dangerously overextended themselves
(E) both rich and poor; great quantities of people were dangerously overextended


OA is C





The spraying of pesticides can be carefully planned, but accidents, weather conditions that could not be foreseen, and pilot errors often cause much larger deposits of spray than they had anticipated.
(A) weather conditions that could not be foreseen, and pilot errors often cause much larger deposits of spray than they had
(B) weather conditions that cannot be foreseen, and pilot errors often cause much larger deposits of spray than
(C) unforeseeable weather conditions, and pilot errors are the cause of much larger deposits of spray than they had
(D) weather conditions that are not foreseeable, and pilot errors often cause much larger deposits of spray than


OA is B

Pls also mention the proper reasoning.I am looking for reasons, not the answers....Pls