To free up more money to pay down his credit card debt, the best option for James would be:
He has to cut back on other expenses.
While reducing rent could help, it's often not feasible to lower a fixed cost like rent without significant changes, like moving. Contributing to his 401(k) would reduce his take-home pay, which would not help his immediate goal of paying down debt. Therefore, identifying and cutting back on discretionary expenses like entertainment, dining out, or clothing would be the most effective strategy for freeing up more funds.