12 Days of Christmas GMAT Competition - Day 2: All of the desserts

Manhattan Prep Official Explanation

Step 1: Identify the Question

The words which of the following must also be true in the question stem indicate that this is an Inference question.

Step 2: Deconstruct the Argument

As is the case with most Inference questions, there is no traditional argument here. Instead, the paragraph contains a list of facts:
(1) The Avery party purchased desserts from Kelsey’s Bakery last Friday.
(2) Kelsey’s Bakery does not produce any desserts that contain nuts.
(3) Because Kelsey’s Bakery does not produce any desserts with nuts, there are certain desserts, such as traditional baklavas, that Kelsey’s Bakery does not make.
(4) Last week, Kelsey’s Bakery made spice cakes, but none of these were sold on Friday.

Step 3: Pause and State the Goal

On Inference questions, the task is to identify which answer choice is completely provable from only the given information. Since this is an Inference EXCEPT variation, four of the choices will be completely provable, and one choice will be either false or not provable. That one false or not provable choice will be the correct answer.

Step 4: Work From Wrong to Right

(A) Since Kelsey’s Bakery does not make any desserts that contain nuts, and since all traditional baklavas contain nuts, Kelsey’s Bakery does not make any traditional baklavas. Kelsey’s Bakery may make baklavas, but if that is the case, those baklavas cannot be traditional baklavas. (Note that this choice uses a conditional if statement: The choice does not state that Kelsey’s Bakery does make baklavas, merely that if it does, then those baklavas are not traditional.)

(B) All of the desserts that the Avery party purchased from Kelsey’s Bakery were purchased last Friday, and none of the spice cakes were sold last Friday, so this statement is provable from the given information.

(C) CORRECT. While it is true that none of the desserts the Avery party purchased from Kelsey’s Bakery would contain nuts, and also true that all of the desserts the Avery party purchased last Friday were from Kelsey’s Bakery, the paragraph makes no mention of whether the Avery party purchased any desserts on other days of the week from other bakeries. It is possible that the Avery party purchased desserts on other days from other bakeries, and these desserts may contain nuts. This statement is not provable from the information given.

(D) Since Kelsey’s Bakery makes spice cakes, there must be some spice cakes (at least the ones made at Kelsey’s Bakery) that do not contain nuts.

(E) While the paragraph makes no mention of carrot cake, it does state that Kelsey’s Bakery makes no nut-containing desserts. As with choice (A), note that this choice uses conditional language: If Kelsey’s Bakery does make carrot cake, that carrot cake must be nut-free.