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: a = 4 ^ 15 - 625 ^ 3 and a / x is an integer , where x is a positive integer greater than 1 , such that it does not have a factor p such that 1 < p < x , then how many different values for x are possible ?
Options: a ) none , b ) one , c ) two , d ) three , e ) four
c

Problem: if a ' s height is 45 % less than that of b , how much percent b ' s height is more than that of a ?
Options: a ) 66.66 % , b ) 81.81 % , c ) 66.766 % , d ) 86.66 % , e ) 66.65 %
b

Problem: how many positive integers between 1 and 300 are there such that they are multiples of 21 ?
Options: a ) 14 , b ) 16 , c ) 17 , d ) 13 , e ) 15
a