Final answer:
The correct phrase to complete the sentence is 'has gone,' indicating that Hans has left to see his grandmother and this action is relevant to his current absence. The use of present perfect tense 'has gone' is appropriate for actions completed in the past but affecting the present.
option 'a' is the correct
Step-by-step explanation:
The sentence 'Hans isn't here. He ____ to see his grandmother. He'll be back tomorrow.' should be completed with the phrase 'has gone.'
This is because the sentence is in the present perfect tense, which suggests that an action has been completed at some point before now, but is still relevant to the present moment. 'Has gone' indicates that Hans left at an earlier time and that this action is relevant now because he is not present.