ChiGMAT wrote:
Although the initial setup of generators and a power grid by Edison and JP Morgan was rather costly, the electrification of lighting in lower Manhattan doubled work efficiency when the energy costs were cut in half.
(A) the electrification of lighting in lower Manhattan doubled work efficiency when the energy costs were cut in half
(B) the electrification of lighting in lower Manhattan doubled work efficiency while cutting energy costs in half
(C) the electrification of lighting in lower Manhattan doubled work efficiency while costs were cut to half
(D) lighting electrification in lower Manhattan doubled work efficiency while energy costs were cut in half
(E) lighting electrification in lower Manhattan doubled work efficiency while costs were cut to half
to
cut X in half is to
reduce X by 50%. Thus, it is idiomatically correct to say
'while cutting energy costs in half'
to mean
'while reducing energy costs by 50%.'
From the above C and E are out.
moreover .. In E costs is ambiguous... We are unable to determine which costs were cut in half. That rules out E.
Coming to the rest of the choices...
Lighting electrification sounds as if it lighting evolved by itself. Not possible. Hence D is ruled out.
Problem with A is the word 'when'. We have to contrast 'doubling of work efficiency 'against 'reduction in energy costs'. Correct word that should be used is 'While'.
Hence the clear winner is
'B'