Quotation marks 3
Example:

“The more anxious we are about eating, the more vulnerable we are to the seductions of the marketer and the expert’s advice.” Pollan reasons (301).

“The more anxious we are about eating, the more vulnerable we are to the seductions of the marketer and the expert’s advice,” Pollan reasons (301).

A quotation should be set off from the signal phrase Pollan reasons with a comma, not a period.