We know that under the condition of being inviting and functional, a work of architecture is not obtrusive.
Therefore:
WA ==> not O
Contrapositive
O ==> not WA
AND
I & F ==> not O
Contrapositive
O ==> not I or not F
(A) is incorrect because it is taking the existence of the necessary condition "unobtrusive architecture," to conclude the sufficient condition "inviting and functional." Remember, you need to reverse and negate, not just reverse!
(B) is CORRECT, but confusing. The key here is the sentence, "Modern architects have violated this precept." From this we gather that modern architects make works of architecture, but those works are obtrusive (thereby violating the main precept). Therefore, (B) is correct because being not unobtrusive is being obtrusive, and we know that modern architects are obtrusive.
(C) is incorrect because we do not know whether or not an architect with a strong personality can or cannot do something from the stimulus.
(D) is incorrect. "A work of architecture that takes second place to the environment" is unobtrusive. What (D) is doing is that it is taking the existence of the necessary condition "unobtrusive architecture" and concludes part of the sufficient "functions well for public use." Remember you can't just reverse, you need to reverse and negate!
(E) is incorrect because we have never discussed whether or not a work of architecture can or cannot express its architect's personality.
Hope that helps! Let me know if you have any more questions!
