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

Q: Problem: what is the units digit of 26 ! + 50 ! + 4 ! + 4 ! ? 
Options: a ) 8 , b ) 6 , c ) 4 , d ) 2 , e ) 0

A: a
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Q: Problem: of 60 children , 30 are happy , 10 are sad , and 20 are neither happy nor sad . there are 18 boys and 42 girls . if there are 6 happy boys and 4 sad girls , how many boys are neither happy nor sad ? 
Options: a ) 2 , b ) 4 , c ) 6 , d ) 8 , e ) 10

A: c
****
Q: Problem: what is the greatest positive integer n such that 3 ^ n is a factor of 36 ^ 50 ? 
Options: a ) 100 , b ) 200 , c ) 300 , d ) 600 , e ) 900

A:
a
****