It looks like to me that letter (A) and letter (D) meet the parallelism rule.
With letter A ---->A fire <etc etc>, making ignition much easier and flames spreading more quickly.
With letter D ---->A fire <etc etc>, making ignition much easier and causing flames to spread more quickly.
In the first, ignition and flames spreading are parallel nouns; in the second, Making and causing are parallels. Is parallelism the real difference between those answer choices? Someone could
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With letter A ---->A fire <etc etc>, making ignition much easier and flames spreading more quickly.
With letter D ---->A fire <etc etc>, making ignition much easier and causing flames to spread more quickly.
In the first, ignition and flames spreading are parallel nouns; in the second, Making and causing are parallels. Is parallelism the real difference between those answer choices? Someone could
...
