I believe D is best.
The construction of the premise is that the conclusion holds because there are 2 given facts that make it so. First, "no one is allowed to teach more than one introductory level class in any one term". Second, "the only language classes being taught next term are advanced ones". Those are the 2 reasons/facts which support the conclusion
Conclusion: "the building with the large public space that was recently completed in Alton will not be subject to city taxes next year"
1st reason: New buildings that include public space are exempt from city taxes for two years
2nd reason: all new buildings in the city's Alton district are exempt for 5 years
IMO, it is the only answer that gives 2 reasons to support the conclusion
E) was confusing but is based on a different reasoning. E says that a building that is exempt from X pays Y and since Founder's hospital is exempt from X then it must be paying Y. E's reasoning is derived from associativity of a subset to a larger group and is not similar to the structure of the stem.