Given the task definition and input, reply with output. In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].

Washington (CNN) One of the most remarkable moments on the campaign trail this week was one that didn't happen. Former Miss Universe Alicia Machado introduced Hillary Clinton at a Florida rally Tuesday, blasting Donald Trump. And for once, the billionaire didn't react. No tweets. No attacks from the stump. Nothing. Instead, he stayed on message going after Clinton on her email server while pledging to repeal Obamacare. In the final days of the 2016 campaign, Trump isn't taking Clinton's bait. The new self-discipline comes as the election tightens and polls indicate a razor-close race in battleground states such as Florida, New Hampshire and Colorado. On the stump Wednesday night in Florida, Trump revealed how he is focused on staying disciplined and how hard it is for him.Trump isn't taking Clinton's baitTrump at Wednesday rally: 'We've got to be nice and cool, nice and cool, right?' 
 Question:A different _ source used a baseball analogy to describe Trump and why he is exhibiting the self-control many thought he didn't have.

Donald Trump