In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Q: Problem: a and b are two circles . the radius of a is four times as large as the diameter of b . what is the ratio between the areas of the circles ? 
Options: ['a ) 1 : 8 .', 'b ) 1 : 2 .', 'c ) 1 : 24 .', 'd ) 1 : 64 .', 'e ) 1 : 6 .']

A: d
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Q: Problem: the area of a square field is 1600 km 2 . how long will it take for a horse to run around at the speed of 16 km / h ? 
Options: a ) 12 h , b ) 10 h , c ) 8 h , d ) 6 h , e ) none of these

A: b
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Q: Problem: the total surface area of a solid hemisphere of diameter 14 cm , is : 
Options: ['a ) 462 cm ²', 'b ) 530 cm ²', 'c ) 1345 cm ²', 'd ) 1788 cm ²', 'e ) none']

A:
a
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