一個片語的用法 (Gathered some momentum) - 英檢

黃金閱讀5.3版的第六篇閱讀

Artisans and Industrialization

...The labor movement gathered some momentum in the decade before the Panic of
1837,....

6.The phrase gathered some momentum in the passage is closest in meaning to
(1 made progress
(2 became active
(3 caused changes
(4 combined force

我是選4 不過答案是1
我記得momentum是動能的意思，所以我覺得可能的意思是
聚集了一些能量，力量
不過我搞不太懂為什麼答案會是1 囧"
有請各位前輩們幫忙解惑

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