Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

[EX Q]: Gastro-esophageal sphincter sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach.
[EX A]: Which sphincter is located at the stomach end of the esophagus and opens to allow the bolus to enter the stomach?

[EX Q]: The love canal tragedy was an infamous example of industrial waste dumping.
[EX A]: Love canal was an infamous example of what type of pollution?

[EX Q]: There are four many visual clues to indicate a chemical reaction.
[EX A]:
There are how many visual clues to indicate a chemical reaction?