The management of a magazine recently divided its staff of writers into two groups based on whether the writers took more than six breaks daily. A higher percentage of those writers who took more than six breaks a day had problems producing article ideas than did the writers who took six breaks or fewer. The management of the magazine concluded that taking more than six breaks per day causes writers to be less productive.

Which of the following, if true, most seriously weakens the conclusion above?


The writers who took more than six breaks daily produced, on average, more articles than did the other writers who took less than six breaks daily.

Some of the writers who took fewer than six breaks daily produced large numbers
of article ideas.

A diminished output of article ideas was the reason that some of the writers who
took fewer than six breaks daily lowered the amount of breaks that they took per day.

Some writers took breaks of only one minute each, while other writers took breaks
of up to twenty minutes each.

Frustration over the low production of article ideas caused some of the writers already taking more than six breaks a day to take even more frequent breaks.