An analogy is a correspondence or comparison between one element or set of elements and another which in most cases aimed at showing the similarities between the elements that compose the analogy. This means an analogy occurs when two elements relate in the same way or the characteristics of an element are transferred to another. In the case of the example presented in the question "laboratory:campus" it suggests the laboratory belongs to the campus, is part of the campus or can be found in the campus, which means the second analogy should accomplish the same feature of belonging, being part or being found to create a correspondence or similarity between both elements. Because of this the best option that completes the analogy is "professor: faculty" as in the same way of "laboratory: campus" the professor somehow belongs to the campus, can be found there or is part of the campus in terms of staff, this means in this way both elements "professor: faculty" and "laboratory: campus" express the same relationship and therefore there is a correspondence or analogy.
