Behavioural economics — practice question

In an economy with two people, X earns $100 and Y earns $50. Under the Pareto criterion, which change in income would count as a clear improvement in economic welfare?

• AX’s income $75; Y’s income $75
• BX’s income $85; Y’s income $70
• CX’s income $95; Y’s income $100
• DX’s income $130; Y’s income $50