Final answer:
Taft's reaction to the stress of being President isn't directly known to fit any of the provided options. He fulfilled his term and faced various challenges, but did not resign or show well-documented signs of distress that would categorize his reactions as provided in the options.
Step-by-step explanation:
How did Taft react to the stress of being President? William Howard Taft's presidency was characterized by several stresses and difficulties, including heightened expectations due to his predecessor, Theodore Roosevelt, and complicated foreign policies that would have long-lasting effects. However, none of the provided answers (a) Calm and collected, (b) Showed signs of distress, (c) Resigned from the position, or (d) Unpredictable reactions directly describe the historical record of Taft's reaction to the stress of being President. Instead, he continued his role until the end of his term, despite the challenges he faced and the eventual split in the Republican party that led to his loss to Woodrow Wilson in the 1912 election.