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

Problem: ashley paid 5 dollars for 1 notebook and 1 pencil . if both prices were integers , how many pencils did ashley buy if she paid 93 dollars for the pencils and for 15 notebooks ? 
Options: a ) 6 . , b ) 16 . , c ) 18 , d ) 21 , e ) 26
d

Problem: the cost of 3 pens and 5 pencils is rs . 260 . also the cost of one pen and one pencil is in the ratio of 5 : 1 respectively . what is the cost of one dozen pens ? 
Options: a ) rs . 200 , b ) rs . 250 , c ) rs . 300 , d ) rs . 780 , e ) none of these
d

Problem: what is the square root of 16 ? 
Options: a ) 8 , b ) 4 , c ) 35 , d ) 42 , e ) 86

b