Answer: C
Explanation: To understand questions like this, first we need to find the flaw(s). Consider the statement; "Not all tenured faculty are full professors"- this is exactly implying that at least one tenured professor isn’t a full professor. Bearing in mind that this applies to the entire university, nothing is saud about full professors with tenure in the Linguistics department. It is possible that there isn't any full professor in the Linguistics department and also possible that the entire linguistics department has only full professors.
The answer choice (C) displays the same flaw. Although famous architects design buildings not well proportioned and all government buildings are by famous architects, the buildings not well proportioned may be privately owned. For all we know, all the government buildings could be well proportioned or none at all could be well proportioned.