Rose: The book is either by Deerson or else by Jones; I’m not sure which. However, Deerson’s books are generally published by Quince Press, as are Jones’s. Therefore, the book is probably published by Quince.
The pattern of reasoning here seems to be on the following line:
The book (X) is either by Deerson (Y) or by Jones (Z). Deerson's (Y) and Jones's (Z) books are generally published by Quince Press (W). Therefore the book (X) is probably published by Quince Press (W).
Abstracting this: X can be attributed to Y or Z; Y and Z generally happen due to W; hence X implies W
The pattern of reasoning in which one of the following is most similar to that in Rose’s argument?
(A) That tree is either a beech or else an elm, and Mercedes can identify most trees, so she will probably be able to tell which it is.
Tree (X) is either a beech (Y) or an elm (Z). Mercedes (W) can identify most trees. The rest of the logic does not follow: Y and Z being tied to W and hence X implying W.
(B) The culprits escaped either by car or else on foot, but in either case they must have opened Isidore’s creaking gate. Therefore Isidore probably heard them.
Culprits (X) escaped either by car (Y) or by foot (Z). They must have done so by opening Isidore's creaking gate (W). The parallelism breaks down by being definitive. We need Y and Z to probably imply W not be definitive. Also, the last sentence should connect the culprits to Isidore (X implies Y) and not Y to X.
(C) Judging by what he said in the interview, George is either a liar or incredibly naive. Both these attributes are unsuitable in a customs inspector. Therefore George should not be hired as a customs inspector.
George (X) is a liar (Y) or naive (Z). Y and Z are unsuitable for a customs inspector (W). Parallel thus far but hence X should not be W breaks the parallelism which should be X implies W; here it says that X does not imply W.
(D) Margarethe the Second was born either in Luppingshavn or else in Kindelberg. Most of the people in each city then were of Mondarian descent, so Margarethe probably had Mondarian ancestors.
Margarethe (X) was born either in X or in Y. Most of X or Y mean Mondarian descent (W) (this is not definitive as in the first example) and hence X probably had W. Seems fully parallel to the example in the question.
(E) Tomas will probably participate in community service, since he will attend either Dunkeld College or Steventon University and at both most students currently enrolled say that they participate in some form of community service.
Tomas (X) will attend Y or Z. Most of Y and Z participate in community service (W). X probably means some form of W as opposed to W itself; also the words 'will' and 'probably' seem contradictory. If it had said 'probably' only, that would have been closer.
I think it is D.