The correct format is "as (Adj) as" possible.
the clause after the comma is a modifier,which has to modify a noun from the previous clause. A,C,D does not contain any such noun (to conserve energy is in a verb form) hence are out.
Between B & D, B incorrectly uses the format as straight in a line as IS possible. Which is incorrect, hence correct choice isE.
Also,[In 'as straight a line' as possible] is better than["As straightly as possible" in a line] .
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the clause after the comma is a modifier,which has to modify a noun from the previous clause. A,C,D does not contain any such noun (to conserve energy is in a verb form) hence are out.
Between B & D, B incorrectly uses the format as straight in a line as IS possible. Which is incorrect, hence correct choice isE.
Also,[In 'as straight a line' as possible] is better than["As straightly as possible" in a line] .
...
