We can see here that the detail that helps to create a tense mood in this excerpt is: Sadako and her father look at each other.
What is mood?
Mood refers to the emotional response that a writer invokes in the reader. It is usually created with the use of words by the writer. It tells us about the atmosphere where the story is taken place.
It's known that mood can be communicated through the use of imagery, conflict, etc. We see that when there is mood, the atmosphere will be changed.
We can see here that the selected answer above is the detail that helps to create tense mood.