Renewable.
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Answer:
A) stratified
Explanation:
Total call including 6500 'yes' and 4100 'no' are 10600 and on each call there was a fifty cent charge. Total charge becomes 5300 $ so this is very straight forward data. And from this test two types of classes are made with cleared population in each class and such cleared population division is example of stratified sampling so this is right answer.