Three terms forms an increasing G.P with ratio r . If the second term of the given G.P is double then the new series are in A.P with common difference d also the 4th terms of G.P is `3r^2` then the value of `(r^2-d)` is

Options

A. `7-3sqrt3`
B. `7-sqrt3`
C. `7+sqrt3`
D. `7+3sqrt3`

Answer

C