`f_(B)` and `f_(R)` are focal lengths of a convex lens for blue and red light respectively and `F_(B_ and Fr are the focal lengths of the concave lens for blue and red light respectively. We must then have

Options

A. `f_(B)gtf_(R)` and `f_(B)ltf_(R)`
B. `f_(B)ltf_(R)` and `f_(B)gtf_(R)`
C. `f_(B)gtf_(R)` and `f_(B)gtf_(R)`
D. `f_(B)ltf_(R)` and `f_(B)f_(R)`

Answer

D