The correct answer is C. Definition 3
Explanation:
In language, it is common a word has more than one literal or dictionary definition, which can be related or not, this means a word can be used in different contexts and sentences, but this also implies it is necessary to understand which meaning is being used in a sentence. Although, this might not seem an easy task, especially with words that have multiple similar meanings it can be done by understanding the different meanings and identifying the context of the sentence and the meaning that can replace the word in that specific sentence.
In the case of the word "robust" there are four main meanings provided the first meaning or "strong and healthy; hardy" describes a quality and therefore can be used to describe people or even animals; the second meaning or "strongly built" can be also sued to describe a person, an animal, and even an object;on the other hand, the third meaning or "requiring bodily strength or endurance" refers to an activity, job or similar that requires strength and endurance and the fourth meaning or " effective in all or most situations" is a synonym of the word effective.
This implies in the case of the sentence "The personal trainer developed a new exercise routine that proved to be too robust for her clients" in which robust is used to describe an activity the definition that clarifies the meaning of the word robust is the definition 3 or "requiring bodily strength or endurance", because this definition refers to an activity or similar that requires a lot of strength which is exactly the case of the sentence presented.
