Step 1: Concept Evolutionary biology and connecting links.
Step 2: Meaning Connecting links show traits of two different taxonomic groups.
Step 3: Analysis * Seymouria is a link between Amphibia and Reptilia (B is correct).
* Eusthenopteron is a link between Fishes and Amphibians (D is correct).
* Peripatus connects Onychophora (not Mollusca).
* Cynognathus is a synapsid reptile, not specifically a bridge between reptiles and birds.