Lobe finned fishes or the Sarcopterygii is a group or clad of fish that contain the coelacanths, tetrapods, lungfish, and other fossil relatives. ray-finned fishes and lob finned fishes are the are sister groups.
The major characteristic feature of this fish is the presence of lobe in their fins. The ancestral records explained that the land-dwelling tetrapods are evolved from the lobe-finned fishes around four four hundred million years ago.
Thus, the correct answer is option B. lobe-finned fish.
Adaptive radiation is the process by which a single specie or
single ancestral lineage, goes through several or various speciation processes and
then become adaptively specialized to a specific or particular environmental or
ecological place.