Answer:
It includes a clear topic sentence and provides effective support.
Step-by-step explanation:
The solidity of a topical sentence in an argument is not enough for an argument to be considered strong: solidity is a necessary but not sufficient condition. An argument can be solid and yet be a weak argument. For the argument to be considered strong, it must have a well-established and solid topical phrase and have effective support to substantiate the message spoken by the topical phrase. An example of this is the paragraph shown in the question, which is a strong argument because it includes a clear topic phrase and provides effective support.