White light is used in a YDSE with $D= 1m$ and $d= 0.9 mm$ .Light reaching the screen at position $y= 1 mm$ is passed through a prism and its spectrum is obtained. The missing lines in the visible region of this spectrum is :-

Question

$(a)\;300\;nm \\ (b)\;600\;nm \\ (c)\;both \;a\; and\; b \\ (d)\;None$