Which of the following words has the short vowel /u/ sound?

The word "stump" features the short vowel /u/ sound, which is characterized by the pronunciation that occurs in words like "cup" and "run." In "stump," the vowel sound is produced with a relaxed mouth position, allowing for the distinct short /u/ sound.

In contrast, while "sun" does have a similar short vowel sound, it is not the word highlighted in the correct answer. The words "sting" and "stone" contain different vowel sounds altogether; "sting" features a long /i/ vowel sound, while "stone" includes a long /oʊ/ sound. Thus, "stump" is a prime example of the short vowel /u/ sound, making it the correct choice in this question.