THE ANSWER IS D! girls had laughed a little nervously. :)
One example of dramatic irony is when the people on the shore see the boat out at sea. They believe that it is a novelty, not that someone might need their help. The people in the boat, see the people on the shore as their rescuers. Both are wrong.
Infinitives typically include the word to.
For example: He likes to swim.
The form <em>to swim </em>is an infinitive - it is the basic form of the verb. It contains the verb itself (swim) and the word TO in front of it. Sometimes TO can be excluded, but usually it is not.