Which word would best complete the sentence: "She was disturbed by the __________ regulations imposed by the committee"?

The choice of the word "stringent" to complete the sentence fits perfectly because it conveys a sense of strictness and rigor associated with regulations. When regulations are described as stringent, it indicates that they are harsh, demanding, and enforceable, which aligns with the idea of disturbance. The context suggests that the person feels unsettled or troubled by the seriousness of the regulations, making "stringent" the most appropriate term to capture that sentiment.

In contrast, the other options present meanings that do not align with the context of the sentence. "Callow" refers to a lack of maturity or experience, which does not relate to the nature of regulations. "Epitome" signifies a perfect example of something and would not make sense in the context of describing regulations. Lastly, "ex officio" pertains to roles and responsibilities inherent in holding a particular office, rather than describing the nature of regulations themselves. Therefore, "stringent" is the logical choice to illustrate the disturbance caused by the committee’s regulations.