instruction:
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.
question:
Sentence: Oxygen has increased in the atmosphere throughout the history of the earth. Question: What has increased in the atmosphere throughout the history of the earth?
answer:
oxygen


question:
Sentence: The base of a nucleotide within dna consists of nitrogen. Question: What does the base of a nucleotide within dna consist of?
answer:
nitrogen


question:
Sentence: We call the study of rock layers stratigraphy. Question: What do we call the study of rock layers?
answer:

stratigraphy