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

Problem: jill ' s favorite number is even and has some repeating prime factors . john is guessing jills favorite number , and the only hint she gives is that 7 is a prime factor . what is johns best guess ?
Options: a ) 84 , b ) 105 , c ) 54 , d ) 42 , e ) 70
a