Explanation:

Introduction:
This question asks us to determine whether the given sentence "The result will be declared soon" is in active voice, passive voice, both active and passive voice, or none of the above.

Active Voice:
In active voice, the subject of the sentence performs the action. The sentence "The result will be declared soon" does not have a clear subject performing the action. Therefore, we can conclude that the given sentence is not in active voice.

Passive Voice:
In passive voice, the subject of the sentence receives the action. The sentence "The result will be declared soon" can be rewritten in the passive voice as "The result will be declared soon by someone/something." Here, the subject "the result" is receiving the action "will be declared." Therefore, we can conclude that the given sentence is in passive voice.

Both Active and Passive Voice:
Some sentences can be written in both active and passive voice. However, in this case, the given sentence does not have a clear subject performing the action. Therefore, we cannot say that it is in both active and passive voice.

Conclusion:
In conclusion, the given sentence "The result will be declared soon" is in passive voice.