In this task, you are given a sentence and a question, you would be asked to create the answer which is contained in the sentence provided.

Sentence: Certain anaerobic parabasalid species exist in the digestive tracts of termites and wood-eating cockroaches, where they contribute an essential step in the digestion of cellulose. Question: Certain anaerobic parabasalid species exist in the digestive tracts of termites and wood-eating cockroaches, where they contribute an essential step in the digestion of this?
cellulose

Sentence: None purpose does the appendix serve in humans today. Question: What purpose does the appendix serve in humans today?
none

Sentence: Ground tilting is caused by the buildup of stress in the rocks. Question: What is caused by the buildup of stress in the rocks?

ground tilting