An interference experiment using a double slit is arranged as illustrated. Fringes appear on the screen. The separation between neighbouring bright fringes is measured as $4\,\text{mm}$. Two alterations are then made to the setup. The double slit is swapped for a different double slit with half the slit spacing. The screen is also shifted so that its distance from the double slit is twice as large. What is the new separation between neighbouring bright fringes?
- A$1\,\text{mm}$
- B$4\,\text{mm}$
- C$8\,\text{mm}$
- D$16\,\text{mm}$