Which of the following developments has caused recent controversy between richer and poorer members of the European Union?

One of the developments that has caused recent controversy between richer and poorer members of the European Union is the allocation of funds in the European Union's budget. Specifically, the debate revolves around the distribution of financial resources and the principle of solidarity among member states.

The controversy stems from the fact that wealthier countries, such as Germany and the Netherlands, have voiced concerns about contributing a disproportionate amount of funds to support the less affluent nations. The argument is that some richer countries believe they are shouldering a heavier financial burden to support the poorer nations, while feeling that those states should be implementing necessary economic reforms to improve their own financial situation.

Some richer countries have expressed displeasure with the European Union's funding mechanism, specifically the Common Agricultural Policy (CAP) and structural funds, which they believe disproportionately benefit poorer nations. Disagreements have also emerged regarding how funds should be allocated to address various regional issues such as migration, security, and economic development.

These controversies have highlighted underlying tensions about redistribution of wealth within the European Union, with wealthier nations seeking fair distribution and accountability for funds, while poorer nations argue for continued support to ensure their economic growth and convergence.