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This region is a natural choke point , where the Qattara Depression creates a relatively short line to defend that could not be outflanked to the south because of the steep escarpment .
 Qattara Depression
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Qattara Depression