Step 1: Understanding the Question:
This question belongs to the topic of English vocabulary and contextual sentence completion.
The sentence describes a direct cause-and-effect scenario where the remarks of the Association President caused an adverse reaction among several committee members.
The reaction of "walking out" indicates that the nature of the remarks was highly provocative, offensive, or controversial.
Step 2: Key Formulas and approach:
Analyze the tone and negative/positive polarity of the context clue "walked out of the meeting".
An extreme action like walking out of a formal meeting suggests a powerful negative stimulus.
Therefore, the blank must be filled with an adjective that carries a strong negative and agitating connotation.
Step 3: Detailed Explanation:
$\bullet$ Option (A) "discreet" means careful and circumspect in one's speech or actions, which would maintain peace rather than cause a walkout.
$\bullet$ Option (B) "interesting" is a neutral or mildly positive word that would typically engage the members rather than drive them away.
$\bullet$ Option (C) "exemplary" means serving as a desirable model or representing the best of its kind, which is highly positive and contradicts the negative outcome.
$\bullet$ Option (D) "inflammatory" means tending to arouse anger, hostility, passion, or severe resentment, which perfectly explains why the members walked out in protest.
Step 4: Final Answer:
Thus, "inflammatory" is the only word that logically and grammatically fits the context of the sentence.