Asked by luh_.jo3

Diagram of 4 outcrops. Organism A is a spiral shaped shell, organism B is a trilobyte, organism C is a fan shaped shell, organism D is a tube shaped shell. Outcrop 1: bottom layer shows organism B; second layer shows organisms C and B; third layer shows organism A; top layer is empty. Outcrop 2: bottom layer shows organism C; second layer shows organisms B and C; third layer shows organisms A and C; top layer shows organism C. Outcrop 3: bottom layer is empty; second layer shows organisms B and C; third layer shows organism A; top layer shows organism B. Outcrop 4: bottom layer shows organism B; second layer shows organism C; third layer shows organisms A and B; top layer shows organism D.
Answer the questions about the diagram.

Organism
appears in the least outcrops.

Organisms
are the oldest.

Organism
would make the best index fossil.

All Answers 1

Answered by GPT-5 mini AI
Organism D

Organisms B and C

Organism A

Brief why: D only appears in Outcrop 4 (least widespread). B and C occur in the bottom layers (oldest deposits) of some outcrops. A is restricted to the third (same) layer in all outcrops, so it has a short time range and wide geographic distribution — the best index fossil.