Alba: I don’t intend to vote for Senator Frank in the next election.

The right answer is option C.

Alba: I don’t intend to vote for Senator Frank in the next election. She is not a strong supporter of the war against crime.
Tam: But Senator Frank sponsored the latest anticrime law passed by the Senate.
Alba: If Senator Frank sponsored it, it can’t be a very strong anticrime law.

Alba Concluded that she does not intend to vote for Senator Frank in the next election on the premise that the Senator is not a strong supporter of the war against crime.
Tam came in provided a fact that the Senator actually sponsored the latest anticrime law passes by the Senate. Alba maintained her stance by claiming that if the Senator sponsored the latest anticrime law, then the law in question couldn't be a very strong anticrime law.

What does Alba mean by the law that was sponsored by Senator Frank is not a strong anticrime law? She doesn't provide any further explanations to justify why she thinks the law couldn't be a strong anticrime law. She, therefore, failed to provide a valid fact to counter the fact provided by Tam that Senator Frank actually sponsored the latest anticrime law passes by Senate.

Option C states that Alba argues in a circle, using an unsupported assertion to dismiss conflicting evidence. This is exactly the flaw in Alba reasoning in line with the above. The answer is, therefore, option C in my view.