When Jake is with his girlfriend, he feels so in love, happy, and content. Because he and his girlfriend text and talk on the phone frequently throughout the day, Jake has set up a special ringtone for his girlfriend. Now, when he hears the ring tone, he feels happy and content. Which of the following is the unconditioned stimulus in this example?a. feeling in love, happy, and content b. Jake's girlfriend c. Jake's phone d. the ring tone