Final answer:
The comparison's organizational structure is subject-by-subject, with the subjects, in this case indoor and outdoor cats, being covered individually one after the other.
Step-by-step explanation:
The organizational structure of the comparison being described is subject-by-subject. This structure is recognized because the subjects, which are indoor cats and outdoor cats, are discussed one at a time, rather than alternating between different points of comparison for both subjects. In a subject-by-subject comparison, one subject is thoroughly examined before moving onto the next subject. Indicators of a point-by-point structure, where each point of comparison is given the same amount of discussion for both subjects, are not present here. The structure described does not follow a point-by-point arrangement because all points about one subject are not followed by all points about the other; instead, each subject is given separate consideration.