”Ralph wormed his way” is an example of?

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Ralph wormed his way though the thicket towards the forest, keeping as far as possible beneath the smoke. Presently, he saw an open space and the green leaves of the edge of the thicket . A smallish savage was standing between him and the rest of the forest, a savage striped red and white, and carrying a spear. He was coughing, and smearing the paint about his eyes with the back of his hand as he tried to see through the increasing smoke.

Ralph launched himself like a cat: stabbed, snarling, with the spear, and the savage doubled up. There was a shout from beyond the thicket and then Ralph was running with the swiftness of fear through the undergrowth. He came to a pig-run, followed it for perhaps a hundred yards and then swerved off. Behind him the ululation swept across the island once more and a single voice shouted three times. He guessed that was the signal to advance and sped away again till his chest was like fire.

Then he flung himself down under a bush and waited for a moment till his breathing steadied. He passed his tongue tentatively over his teeth and lips and heard far off the ululation of the pursuers.

A. irony
B. apostrophe
C. metaphor
D. allusion

Correct Answer:

Option D – allusion