Passage Summary: Since humans and all other known creatures are built from the same basic parts and blueprints, they must have started from the same place.

Conclusion: Humans and all other known living things share a common origin.

Reasoning: All known life forms share specific physical and biological characteristics, such as being carbon-based and possessing genetic codes.

Analysis: This argument makes a significant leap from 'sharing traits' to 'sharing a beginning.' To make this conclusion logically airtight, we need a rule that guarantees this connection. Look for an answer that states if different life forms share these specific biological markers, they must have evolved from the same source. Without this bridge, it is theoretically possible for different life forms to have developed the same traits independently from different origins.