Choice "B" is correct. During a period of high inflation, those with a fixed amount of debt will repay their debt with inflated dollars and are thus likely to gain.
Choice "a" is incorrect. Those with a fixed income will see the purchasing power of their income erode and are thus likely to be hurt.
Choice "c" is incorrect. Those holding a large amount of money will see the purchasing power of their money erode and are thus likely to be hurt.
Choice "d" is incorrect. Cost of living adjustments take inflation into account, but fixed wage contracts with no cost of living adjustments have less earnings power.