Concept:Use the present perfect continuous tense for an action that started in the past and is still happening now.Explanation:The phrase "since the stranger entered the house" shows the barking began in the past.It is still continuing at the present moment.The present perfect continuous tense is formed with "has been" plus the present participle.Therefore, the correct phrase is "has been barking."The action is not finished, so choices B, C, and D do not fit the time clue "since."Answer:A. has been