The choices can be found elsewhere and as follows:
A)recent changes in model analyses of the morphological features of animal phyla
B)new tests on fossils for common ancestral appendage types across phyla
C)the discovery of a regulatory protein for muscles in many different phyla
D)the discovery of the "distal-less," or Dll, gene in many different phyla
I think the correct answer is option C. The recent experimental evidence would be the discovery of a regulatory protein for muscles in many different phyla. Hope this helped. Have a nice day.