In this task, you need to provide the correct option for a given problem from the provided options.

[EX Q]: Problem: what is the square root of 261,121 ? 
Options: a ) 476 , b ) 489 , c ) 497 , d ) 511 , e ) 524
[EX A]: d

[EX Q]: Problem: 60 kg of an alloy a is mixed with 100 kg of alloy b . if alloy a has lead and tin in the ratio 3 : 2 and alloy b has tin and copper in the ratio 1 : 4 , then the amount of tin in the new alloy is ? 
Options: a ) 24 kg , b ) 44 kg , c ) 20 kg , d ) 30 kg , e ) 52 kg
[EX A]: b

[EX Q]: Problem: a student committee on academic integrity has 42 ways to select a president and vice president from a group of candidates . the same person can not be both president and vice president . how many candidates are there ? 
Options: a ) 7 , b ) 8 , c ) 9 , d ) 10 , e ) 11
[EX A]:
a