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

Q: Problem: two spherical balls lie on the ground touching . if one of the balls has a radius of 10 cm , and the point of contact is 12 cm above the ground , what is the radius of the other ball ( in centimeters ) ? 
Options: a ) 14 , b ) 15 , c ) 16 , d ) 18 , e ) 20

A: b
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Q: Problem: 9 spheres of the same size are made from melting a solid cylinder of 16 cm diameter and 12 cm height . what is the diameter of each sphere ? 
Options: ['a ) 4 cm', 'b ) 6 cm', 'c ) 8 cm', 'd ) 10 cm', 'e ) 12 cm']

A: c
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Q: Problem: without stoppages , a train travels certain distance with an average speed of 400 km / h , and with stoppages , it covers the same distance with an average speed of 360 km / h . how many minutes per hour the train stops ? 
Options: a ) 3 , b ) 4 , c ) 5 , d ) 6 , e ) 7

A:
d
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