The question stem mentions two opinions -
1) Some say that the standard of living of a person improved at an unprecedented rate during industrial revolution.
2) Others did not agree with the above statement. Only the overall growth of economy has improved. The standard of living did not improve significantly until 20th century.
Statement 2 is the main conclusion. The question asks to complete the blank. So, we need to find a strengthener.
Pre-thinking -
a) Any form of evidence that says that the standard of living was indeed bad or got worse or did not get better until 20th century
b) Any information that says that improvement in standard of living during industrial revolution was not possible.
Option Analysis -
A. social writings from this time indicate that workers' living conditions deteriorated during the revolution.
This option is along the lines of pre-thinking a.
CorrectB. the revolution affected not just the professional lives but also the everyday lives of people at the time.
This option does not tell whether the effect was positive or negative.
WrongC. new manufacturing processes led to marked improvements in the efficiency of the production process across various kinds of industries
This option does not tell how improvement in efficiency impacted the standard of living.
WrongD. classical economics does not even mention the possibility of sustained economic growth during the revolution
This option is irrelevant. There is no mention of classical economics or sustained economic growth in the passage.
WrongE. most economists now believe that socioeconomic changes during the revolution occurred as a rapid rather than gradual process
This option does not tell whether the socioeconomic changes are positive or negative.
Wrong