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 ® 2
5. (a) has small fin on back near tail ® 6
(b) has no fin on back near tail ® 7
6. (a) has barbs near the mouth ® catfish
(b) does not have barbs near the mouth ® 10

according to this dichotomous key, any catfish must have
a double dorsal fin, a small fin on the back near the tail, and barbs near the mouth.
a single dorsal fin, no small fin on the back near the tail, and barbs near the mouth.
a double dorsal fin, a small fin on the back near the tail, and no barbs near the mouth.
a single dorsal fin, a small fin on the back near the tail, and barbs near the mouth.