Explanation:

- The sentence describes a current capable of carrying away large tree trunks, suggesting it is strong and forceful.

- Option 1: Compelling - This means something is convincing or fascinating, but it doesn't fit the context of a physical force.

- Option 2: Powerful - This fits well as it describes a strong current able to carry heavy objects, like tree trunks.

- Option 3: Powerless - This means lacking power, the opposite of what's needed here, as a powerless current couldn't move tree trunks.

- Option 4: Gentle - This indicates a soft or mild force, unsuitable for moving large objects such as tree trunks.

- Option 5: Persuasive - Similar to 'compelling,' this refers to influencing people's minds, not a physical current.