Problem Solving

P,Q,R are positive integers such that Q is a factor of R and R is a multiple of P,which of the following must be an integer

a) (p+q)/r

b) (r+p)/q

c)p/q

d)pq/r

e)r(p+q)/pq

I am confused between choice b and e after substituting numbers at random.Please help

Thanks
Gmatterz