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: the radius of a sphere is increased by 10 % . the surface area increases by ? 
Options: ['a ) 21 %', 'b ) 31 %', 'c ) 41 %', 'd ) 51 %', 'e ) none of these']

A: a
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Q: Problem: a cubical block of metal weighs 5 pounds . how much will another cube of the same metal weigh if its sides are twice as long ? 
Options: ['a ) 48', 'b ) 40', 'c ) 24', 'd ) 18', 'e ) 12']

A: b
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Q: Problem: for a right angle triangle the hypotenuse is 5 and base is 3 . what is the area of the triangle ? 
Options: ['a ) 6', 'b ) 7', 'c ) 8', 'd ) 9', 'e ) 10']

A:
a
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