To make the central fringe at the center`O` , mica sheet of refractive index `1.5` is introduced Choose the corect statement.
A. The thickness of sheet is `(d^(2))/(D)` in front of `S_(1)`
B. The thickness of sheet is `(d^(2))/(D)` in front of `S_(2)`
C. The thickness of sheet is `(d^(2))/(2D)` in front of `S_(1)`
D. The thickness of sheet is `(d^(2))/(2D)` in front of `S_(1)`
