In this task, you need to provide the correct option for a given problem from the provided options.
Q: Problem: the ratio of boarders to day scholars at a school is 7 to 16 . however , after a few new students join the initial 560 boarders , the ratio changed to 1 to 2 , respectively . if no boarders became day scholars and vice versa , and no students left the school , how many boarders joined the school ?
Options: a ) 48 , b ) 64 , c ) 70 , d ) 80 , e ) 84
A:
d