The conclusion is the last sentence, "Therefore, nothing can ever be definitively proved with a photograph."
Why? Because a photograph "could always have been made to show things differently than it does, it cannot express the whole truth, and in that sense, is false."
This is a Strengthen with Sufficient Premise question ("assumption that would be permit the conclusion above to be properly drawn?") so we are looking for the answer choice that 100% guarantees the conclusion here that "nothing can ever be definitely proved with a photograph."
Let's take a look at (A) now:
"Whatever is false in the sense that it cannot be express the whole truth cannot furnish definitive proof."
FCEWT ==> not FDP
Notice that the premise set forth in the stimulus is that a photograph "cannot express the whole truth, and in that sense, is false", which is the sufficient condition of the principle in (A), i.e., FCEWT.
As such, this principle would be invoked, allowing us to conclude, with 100% certainty, that a photograph "cannot furnish definitive proof" (i.e., the necessary condition of the principle in (A), i.e. not FDP, and the conclusion of the stimulus).
Therefore, (A) would be the correct answer.
Hope that helps! Please let us know if you have any other questions.
