The question brings a table with information about the DNA and amino acids sequences for cytochrome c. The question is asking about the organism in the table that is closer to dolphin.
Step 1.
First we must exclude the most genetically distant organisms.
The invertebrates Amoeba and Spoge are the ones that are most distant, having sequences most differents than the other organisms in the table, as well as the dolphin. The first amino acid is the criterion to exclude those organisms.
Step 2.
The Lizard, Earthworm, and Shark also have differences in the amino acid seuence for the citochrome c, being more genetically distant than the other animals in the table.
Step 3.
The mammals are the most similar in DNA and amino acids sequences (cat, kangaroo, and dolphin), but to know which one is closer to dolphins we must analyze in detail the data that the question brings.
Amino acid sequence
Cat - have two different amino acids;
Kangaroo- have two different amino acids.
(both have identical sequences between them)
DNA sequences
Cat- there are differences in nucleotides;
Kangaroo- the sequence is identical, even though the amino acids are not all equals.
Step 4.
With the information of the question and the data analyzed, we can conclude that the Kangaroo is the genetically closer to the dolphins between the organisms used as examples for the question.