In an astronomincal telescope, the distance between the objective and the eyepiece is 36cm and the final image is formed at infinity. The focal length `f_(0)` of the objective and the focall length `f_(e)` of th eeyepiece are
A. `f_(0)=45` cm and `f_(e)=-9cm`
B. `f_(0)=50` cm and `f_(e)=10cm`
C. `f_(0)=7.2` cm and `f_(e)=5cm`
D. `f_(0)=30` cm and `f_(e)=6cm`
