Answer:
Shhh, or you will spoil the surprise!
Explanation:
A future tense is a tense form that talks about something or an event that will happen in the future. In other words, the future tense is a verb tense that describes something that will happen later, in the future.
Among the given sentences, the second sentence "Shhh, or you will spoil the surprise!" is in the future tense. The use of the helping verb "will" indicates a future event or action. And by using “will spoil”, the speaker indicates that the action is not done yet.
Thus, the correct answer is the second option.