Each question has four sentences. One or more sentences may be incorrect in grammar or meaning. Identify the sentence(s) that are incorrect.
A. Psychological research suggests that daily outdoor walking helps adults reduce anxiety levels and improves cognitive clarity during work hours.
B. Although the international literature festival attracted world-renowned authors across the globe, but local participation remained surprisingly low throughout the event.
C. The finance minister stressed that the economy cannot regain stable growth momentum unless domestic industrial production does not increase significantly.
D. Scientists observed that the rare bird species migrates southward during early winter to avoid severe freezing temperatures in Northern Europe.