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.

Example Input: Sentence: Hydrogen gas is generated by the reaction of nitric acid and elemental iron else. Question: Hydrogen gas is generated by the reaction of nitric acid and what else?
Example Output: elemental iron

Example Input: Sentence: Electrostatic repulsions normally prevent a positively charged particle from colliding and reacting with a positively charged nucleus, but may be overcome by kinetic energy. Question: What normally prevent a positively charged particle from colliding and reacting with a positively charged nucleus, but may be overcome by kinetic energy?
Example Output: electrostatic repulsions

Example Input: Sentence: Ph food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin. Question: When food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin?
Example Output:
ph