Refer to this portion of a dichotomous key for fish identification to answer the question.1. (a) Has a single dorsal fin ® 5 (b) Has a double dorsal fin ® 25. (a) Has small fin on back near tail ® 6 (b) Has no fin on back near tail ® 76. (a) Has barbs near the mouth ® Catfish (b) Does not have barbs near the mouth ® 10According to this dichotomous key, any catfish must have

To reach Catfish, follow the key’s steps: at step 1, choose “has a single dorsal fin,” which leads to step 5. At step 5, choose “has a small fin on the back near the tail,” leading to step 6; then choose “has barbs near the mouth.” So a catfish must have a single dorsal fin, a small fin near the tail, and barbs near the mouth.

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