Sentence Correction (SC) | Re: Compared to those who do not, running three days a week saves

(A) isn't parallel: it compares people ("those who do not...") with running itself.

(C) isn't parallel: it compares "not running" with people ("those running for...")

Remember: The use of WHEN is always wrong in such a situation. It means only at that moment when the comparison is made will people save money … absurd!

(D) and (E) misuse "when". You cannot use "when" unless you are literally talking about the timeframe in which an event takes
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