Here is the matching of each characteristic to the appropriate climate cycle:
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Moves along the East Coast of the United States: Gulf Stream
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Changes course every four to five years: El Niño
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Occurs when trade winds decrease in strength: El Niño
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Causes Europe to be warmer than it would otherwise be: Gulf Stream
So your choices would look like this:
- Moves along the East Coast of the United States: Gulf Stream
- Changes course every four to five years: El Niño
- Occurs when trade winds decrease in strength: El Niño
- Causes Europe to be warmer than it would otherwise be: Gulf Stream