In the Section "Investigating Life: Discovering the 'Fishapod'",the Forelimbs of Tiktaalik

In the section "Investigating Life: Discovering the 'Fishapod'",the forelimbs of Tiktaalik have bones,but are fringed with fins instead of toes (Fig.20.57) .Which of the following is the best explanation for this observation?

A) This is a transitional fossil,and the species has not yet lost its arm bones.
B) This is a common ancestor to all of the modern fish species that have bones in their forelimbs.
C) This is a common ancestor to all of the modern amphibian species that have fins on their forelimb.
D) This is a transitional fossil,and the species has not yet lost its fins.
E) This species was an evolutionary dead end,which is why no modern species have both bones and fins on their forelimbs.