I want to go with E which is not the official answer.
In the second quarter of this year, unemployment rates dropped sharply due to spending by consumers in such amounts so that retailers around the country have converted temps to full-time and hired new employees.
A. due to spending by consumers in such amounts so that retailers around the country have converted temps to full-time
B. due to consumer spending in such amounts that retailers around the country would convert temps to full-time
C. because consumers' spending in amounts such that retailers around the country would convert temps to full-time
D. because spending by consumers in amounts so high as to make retailers around the country convert temps to full-time
E. because consumers were spending in such amounts that retailers around the country have converted temps to full-time
There is a difference in using due to and because
Due to is used to give reason for a noun and is followed by a noun
Because of is used to give reason for verb and is followed by a Clause.
In E unemployment rates dropped sharply is being followed by Clause. Tense is also fine. It is straight forward too.
i do not see a good reason to eliminate it.