The correct option to complete the sentence "Do you know if the new teacher .... yet?" is C. has arrived. Let's break down why this is the best choice and why the other options are less suitable. Explanation of the Correct Answer (C. has arrived)

1. Understanding Present Perfect Tense: The phrase "has arrived" is in the present perfect tense. This tense is used to indicate an action that occurred at an unspecified time in the past and has relevance to the present moment. In this case, the arrival of the new teacher is significant because it affects the current situation (i.e., whether the teacher is available for classes).
2. Contextual Relevance: The use of "yet" in the sentence suggests that the speaker is inquiring about whether the action (the teacher's arrival) has occurred up to the present moment. The present perfect tense is perfect for this context because it connects the past action (the teacher arriving) to the present situation (the speaker wanting to know if the teacher is here now).

Why the Other Options Are Incorrect

• A. is arrived: This option is grammatically incorrect. The verb "arrive" does not take the form "is arrived." The correct form would be "has arrived" for the present perfect tense. Therefore, this option is not valid.
• B. will be arriving: This option uses the future continuous tense, which indicates an action that will be happening at a specific time in the future. The sentence is asking about the current status of the teacher's arrival, not a future event. Thus, this option does not fit the context of the question.
• D. had arrived: This option is in the past perfect tense, which is used to describe an action that was completed before another action in the past. Since the sentence is inquiring about the current status of the teacher's arrival, the past perfect tense is not appropriate here. It implies that there was another past event that is not mentioned, making this option irrelevant.

Summary of Key Points

• Present Perfect Tense: "has arrived" indicates an action relevant to the present.
• Contextual Clue: The word "yet" suggests the inquiry is about the current status of the teacher's arrival.
• Grammatical Accuracy: "is arrived" is incorrect; "will be arriving" and "had arrived" do not fit the context of the question.

Revision Summary

• The correct answer is C. has arrived.
• Present perfect tense connects past actions to the present.
• "Yet" indicates a current inquiry about the teacher's arrival.
• Other options are grammatically incorrect or contextually irrelevant.