Sentence Correction (SC) | Re: The percentage of people aged 25–44 living alone increased abruptly be

I am still confused. Why is C wrong? Since A used living which I thought is wrong because it should be past tense not present continuous. Please explain where I am going wrong

Also, I always try to avoid -ing verbs because I read it somewhere that GMAT doesn't like them... Which cases is it ok to use -ing verbs?

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