Over the course of the eighteenth century, the average output of ironwork tripled as a result of several improvements in blowing machinery and because coal replaced charcoal as the fuel used in the smelting of iron ore.
A) Over the course of the eighteenth century, the average output of ironwork tripled as a result of several improvements in blowing machinery and because coal replaced charcoal as the fuel used in the smelting of iron ore.
i didn't pick this answer because i carelessly thought "as a .." and " because coal.." are not parallel. But now i realize they are. A clause and a clause.Moreover, both of them give answers of why was the output tripled
B) Over the course of the eighteenth century a tripling in the average output of ironwork was due to the replacement of charcoal by coal for the fuel used in the smelting of iron ore, in addition to several improvements in blowing machinery.
1)can "over the ..." modify "a tripling"? . for me the answer is yes. it is an prep modifier tells us about when did this tripling happen,similar to "in eighteen century". 2)"Due to" must be used to modify a noun. It cannot be used to explain a whole centence. So i eliminated answer B because of this reason. am i right? 3) the usage of "in addition to" is wanting. i have no idea at all. i tried to search for Ron's post about this grammar usage but failed.
C) With charcoal's being replaced by coal as the fuel used in the smelting of iron ore and several improvements in blowing machinery, the average output of ironwork tripled over the eighteenth century.
1)"with charcoal's being replaced" is correct for me since what we want to emphasize is the action of replacement. 2)can "with ...' modifier used to explain something?
D) The replacement of charcoal with coal for the fuel used in the smelting of iron ore and several improvements in blowing machinery, the average output of ironwork tripled over the eighteenth century.
killed it
E) Charcoal being replaced by coal as the fuel used in the smelting of iron ore, and several improvements in blowing machinery, which tripled the average output of ironwork over the course of the eighteenth century.
killed
OA:A