The correct word to complete the sentence is "synchronize." Therefore, the full sentence will be "So that we could act together, we took a moment to synchronize."
We can arrive at this answer because:
In the sentence shown above, the narrator presents that he wants to act together, at the same time as someone else. This means that the other person wants to act in sync with another person. Therefore, the word "synchronize" is the one that best fits the sentence's context.
You can find more information on what context clues are at the link:
https://brainly.com/question/3173253