Compared with last year,our pay _____ about $500 every month

Compared with last year,our pay _____ about $500 every month.
Compared with last year,our pay _____ about ￥500 every month.
A.has increased byx05x05x05x05x05B.has increased C.increased byx05x05x05x05x05x05D.increased to
课本是这样的the population is creasing by 80 million every year.但是上一道题是B 而不是A?