I initially chose D. But re-reading the question, B makes sense. Why?
Pedro: Unlike cloth diapers, disposable diapers are a threat to the environment. Sixteen billion disposable diapers are discarded annually, filling up landfills at an alarming rate. So people must stop buying disposable diapers and use cloth diapers.
Maria: But you forget that cloth diapers must be washed in hot water, which requires energy. Moreover, the resulting wastewater pollutes our rivers. When families use diaper services, diapers must be delivered by fuel-burning trucks that pollute the air and add to traffic congestion.
Maria objects to Pedro's argument by
(B) indicating that Pedro draws a hasty conclusion, based on inadequate evidence about cloth diapers.Use of word "must" and no mention of cloth diapers clearly show that Pedro has drawn a hasty conclusion about disposable diapers without even finding about cloth diapers.
(D) demonstrating that cloth diapers are a far more serious threat to the environment than disposable diapers are.Maria's argument doesn't contain any comparison. She merely mentioned negative impact of cloth diapers.
My dad once said to me: Son, nothing succeeds like success.