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

Q: Problem: in n is a positive integer less than 200 , and 18 n / 60 is an integer , then n has how many different positive prime factors ? 
Options: a ) 2 , b ) 3 , c ) 5 , d ) 6 , e ) 8

A: a
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Q: Problem: 11 + 12 + 13 + . . . 51 + 52 = ? 
Options: a ) 1361 , b ) 1362 , c ) 1323 , d ) 1364 , e ) 1365

A: c
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Q: Problem: the operation is defined for all integers a and b by the equation ab = ( a - 1 ) ( b - 1 ) . if x 20 = 190 , what is the value of x ? 
Options: a ) 10 , b ) 12 , c ) 11 , d ) 13 , e ) 14

A:
c
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