Final answer:
The description that worst describes Tom is 'racist'.
Step-by-step explanation:
Based on the information provided, the description that worst describes Tom is 'racist'. Tom Watson, a leading Southern Populist, sought to unite poor white Southerners against the elite landowning families he believed still controlled the state through the Democratic Party. While the details of Tom's beliefs are not explicitly mentioned in the given information, it is implied that his views were likely racially biased and discriminatory.