Sheila C. Bair, president, Washington College (MD), writes: Donald J. Trump has made bold and provocative campaign promises on taxes, trade, immigration and infrastructure. These pledges are all in service of bolstering our economic future. While we hope these initiatives will help our economic prospects, there is one important measure missing from the debate. And it could have an even more immediate and direct impact on economic growth: student debt relief. Student debt relief is smart economics and smart politics for the new administration.