var outputConfig = new KnowledgeAgentOutputConfiguration
 {
     Modality = KnowledgeAgentOutputConfigurationModality.AnswerSynthesis,
     IncludeActivity = true
 };

  var agent = new KnowledgeAgent(
      name: "agent",
      models: new[] { agentModel },
      knowledgeSources: new[] { knowledgeSourceReference }
  )
  {
      OutputConfiguration = outputConfig
  }; 

Based on the code I was able to see LLM-generated response