Question

great white sharks and lampreys have fewer similarities in their mouths than great white sharks and piranhas have. lampreys do not have jaws like great white sharks and piranhas do. this piece of evidence supports the following claim:
great white sharks share a more recent common ancestor with piranhas than with lampreys.
which additional piece of evidence best supports the same claim?
great white sharks have pointy scales made of dentine covered in enameloid,
which is a hard, mineralized layer. piranhas have smooth scales made of thin
layers of bone, with no dentine or enameloid. lampreys do not have scales.
great white sharks have teeth made of bone - like dentine covered in
enameloid, which is a hard, mineralized layer. piranhas have teeth made of
the compact dentine covered in enameloid. lampreys have teeth made of the
protein keratin.
great white sharks have five pairs of gills, with each gill slit covered by a
separate skin flap. piranhas have four pairs of gills covered by a single bony
flap on each side. lampreys have seven pairs of gills, each leading to a
separate uncovered opening.

Explanation:

The claim is about the evolutionary relationship (common ancestor) of great - white sharks with piranhas and lampreys. In evolutionary biology, more similarities in anatomical structures (especially those with a genetic basis) suggest a more recent common ancestor.

• For the first option (about scales): Great - white sharks and piranhas have different types of scales (pointy vs smooth), but lampreys have no scales. This does not show a strong similarity between great - white sharks and piranhas.
• For the second option (about teeth): Great - white sharks and piranhas both have teeth with enameloid (a hard, mineralized layer), while lampreys have teeth made of keratin (a different material). This shows a similarity between great - white sharks and piranhas that is not shared with lampreys.
• For the third option (about gills): Great - white sharks and piranhas have different numbers of gill pairs and different coverings, and lampreys have a different structure altogether. This does not show a strong similarity between great - white sharks and piranhas.

Answer:

The second option (Great white sharks have teeth made of bone - like dentine covered in enameloid, which is a hard, mineralized layer. Piranhas have teeth made of compact dentine covered in enameloid. Lampreys have teeth made of the protein keratin) best supports the claim.