The stimulus tells us that computer experts are occasionally asked to allocate funds for new hardware and software for the company.
These computer experts often choose cutting-edge technologies out of personal preference. However, these new technologies are both expensive and full of undiscovered "bugs." Therefore, they are not the most profitable investments (and by extension, likely not the best choice for the company as a whole).
So, what is the principle illustrated by the stimulus?
The principle is threefold:
(1) People have a responsibility to choose
(2) They tend to make choices based on their personal interests
(3) These choices are not necessarily the best ones for the wider group
Notice that this principle is directly reflected in answer choice (C).
(1) People have a responsibility to choose - the librarians have a responsibility to choose books for the library
(2) They tend to make choices based on their personal interests - the librarians choose the books that they enjoy reading
(3) These choices are not necessarily the best for the wider group - the books that are selected are not necessarily those that serve the interests of the community
Answer choice (A) is close, but it is lacking the third element of the principle. There is nothing in the answer choice which indicates that promoting executives on the basis of shared professional interest as opposed to level of education harms the company or is not in the best interests of the company.
Hope this helps! Please let us know if you have any further questions.