Answer:

To determine the correct answer for this question, we need to understand the concept of passive voice and how it is used in sentences.

Passive Voice:
In passive voice, the subject of a sentence is the receiver of the action rather than the doer of the action. The structure of a passive sentence is:
[Object] + [be verb] + [past participle] + [by + subject (optional)]

Now let's analyze the given question and its options:

Question Analysis:
The question states that thousands of kites are being exhibited at the International kite festival. We need to choose the correct option that completes the sentence in passive voice.

Option Analysis:
a) are being exhibited
b) exhibited
c) being exhibited
d) is being exhibited

Option A: are being exhibited
This option correctly uses the present continuous tense in the passive voice. The subject "thousands of kites" is the receiver of the action "being exhibited." The verb "are" is the present tense form of the verb "be," and "being exhibited" is the past participle of the verb "exhibit." This option is grammatically correct and conveys the intended meaning.

Option B: exhibited
This option uses the past tense form of the verb "exhibit." However, it does not use the passive voice structure. The subject "thousands of kites" should be the receiver of the action, but in this option, it appears as the doer of the action. Therefore, this option is incorrect.

Option C: being exhibited
This option uses the present continuous tense in the passive voice, similar to option A. However, it is missing the appropriate form of the verb "be." The correct form should be "are being exhibited" instead of "being exhibited." Therefore, this option is grammatically incorrect.

Option D: is being exhibited
This option uses the present continuous tense in the passive voice, but it incorrectly uses the singular form of the verb "be" ("is") instead of the plural form ("are"). Therefore, this option is grammatically incorrect.

Conclusion:
Based on the analysis above, the correct answer is option A: "Thousands of kites are being exhibited at the International kite festival." This option uses the present continuous tense in the passive voice, correctly using the plural form of the verb "be" and the past participle form of the verb "exhibit."