Both bondface text plays a role like a conclusion. The first, "Increasing the frequency of anti-smoking warnings may be ineffective", is the main conclusion of the passage, while "it may weaken all anti-smoking messaging by leading people to believe that such warnings are needlessly stringent" is also a conclusion, but subordinate to the first.
Answer choices:
(A) The first is a conclusion for which support is provided, but it is not the main conclusion of the argument; the second is an unsupported premise that supports the main conclusion of the argument.
No, that's does not fit with our previous interpretation.
(B) The first is a premise that supports the argument’s only explicit conclusion; so is the second.
No, that's does not fit with our previous interpretation. The first is not a premise.
(C) The first is the only explicit conclusion of the argument; the second is a premise that supports that conclusion.
No, that's does not fit with our previous interpretation. The first is not the only conclusion as well as the second is not a premise for the first.
(D) The first is the main conclusion of the argument; the second lends support to that conclusion and is itself a conclusion for which support is provided.
Yes that's one sounds correct. The first is the main conclusion of the argument and the second is a conclusion itself but also support the first one.
(E) The first is a premise that supports the only conclusion of the argument; the second is that conclusion.
No, that's does not fit with our previous interpretation. The first is not a premise.
Answer: D