Passage Summary: We know that Pteropsida are all tracheophytes and that no tracheophyte can be a chordate; from this, the author concludes that Pteropsida can't be Hominidae.

Conclusion: No members of the Pteropsida group belong to the Hominidae family.

Reasoning: Chordates and tracheophytes are mutually exclusive groups, and every member of Pteropsida is classified as a tracheophyte.

Analysis: This is a classic formal logic 'gap' puzzle. We are given the chain: Pteropsida → Tracheophyte → NOT Chordate. The conclusion jumps to: Pteropsida → NOT Hominidae. To make this logically airtight, we need a link between Hominidae and Chordates. Specifically, if all Hominidae are Chordates, then because Pteropsida are definitely not Chordates, they couldn't possibly be Hominidae. Look for a bridge that connects the 'new' term in the conclusion (Hominidae) to the 'old' term in the premises (Chordates).