In the conversation provided, the correct tener idiom that correctly completes the sentence is "tengo pensado."
Here's why:
1. The context of the conversation is about Roberto expressing his desire to work as a volunteer next summer and travel through Europe.
2. In response, Julio should use an idiom that expresses his intention or plan related to the topic discussed.
3. "Tengo pensado" translates to "I intend to" or "I plan to," which fits perfectly in this context, showing Julio's future intention or plan regarding the topic of conversation.
4. Therefore, the most appropriate choice among the options given is "C. tengo pensado."
By using "tengo pensado," Julio indicates that he has a plan or intention related to the topic discussed, making it the most suitable option to complete the conversation accurately.
