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'.

Problem: the product of two numbers is 2028 and their h . c . f is 13 . the number of such pairs is : 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 4 , e ) 5
b

Problem: a is two years older than b who is twice as old as c . if the total of the ages of a , b and c be 12 , the how old is b ? 
Options: a ) 10 years , b ) 4 years , c ) 6 years , d ) 15 years , e ) 16 years
b

Problem: set # 1 = { a , b } set # 2 = { k , l , m , n , o , p } there are these two sets of letters , and you are going to pick exactly one letter from each set . what is the probability of picking at least one vowel ? 
Options: a ) 1 / 6 , b ) 1 / 3 , c ) 7 / 12 , d ) 2 / 3 , e ) 5 / 6

c