This is a paraphrasing task. In this task, you're given a sentence and your task is to generate another sentence which express same meaning as the input using different words.

the union has also been a bearer of prosperity , because it is an effective mechanism for lagging members to surmount long-standing barriers to development .
the union is also a carrier of prosperity , because it functions as an effective mechanism that forces the lagging member countries to overcome long-term obstacles to development .