Nag coiled himself down, coil by coil, round the bulge at the bottom of the water-jar, and Rikki-tikki stayed still as death. After an hour he began to move, muscle by muscle, toward the jar. Nag was asleep, and Rikki-tikki looked at his big back, wondering which would be the best place for a good hold. "If I don't break his back at the first jump,” said Rikki, "he can still fight; and if he fights—Oh, Rikki!” He looked at the thickness of the neck below the hood, but that was too much for him; and a bite near the tail would only make Nag savage.

"It must be the head,” he said at last; 'the head above the hood; and when I am once there, I must not let go.”

Then he jumped. The head was lying a little clear of the water-jar, under the curve of it; and, as his teeth met, Rikki braced his back against the bulge of the red earthenware to hold down the head.

How does the protagonist move the plot forward in this excerpt?

Nag moves the plot forward by establishing a conflict.
Nag moves the plot forward by planning to reach a goal.
Rikki-tikki moves the plot forward by raising a question.
Rikki-tikki moves the plot forward by trapping Nag in the jar.