In which context would "noxious" most likely be used?

The term "noxious" is often associated with harmful or toxic effects. It is commonly used in contexts involving substances that can cause damage to living organisms, such as pollutants in the environment or certain chemicals. Therefore, referring to harmful substances aligns perfectly with the meaning of "noxious."

In contrast, the other options describe positive or neutral circumstances. For example, "delightful fragrance" evokes pleasantness, "nutritious food" implies health benefits, and "beneficial relationships" reflect positive interactions. Each of these choices stands in opposition to the implications of harm and toxicity inherent in the term "noxious." Thus, option B effectively captures the essence of the word, making it the most appropriate context for its usage.