Answer:
b. 0.25cm
Step-by-step explanation:
You can solve this question by using the formula for the position of the fringes:
![y=(m\lambda D)/(d)](https://img.qammunity.org/2021/formulas/physics/high-school/9e60g3vc6882m6t31867off1u74vwbdk50.png)
m: order of the fringes
lambda: wavelength 500nm
D: distance to the screen 5 m
d: separation of the slits 1mm=1*10^{-3}m
With the formula you can calculate the separation of two adjacent slits:
![\Delta y=((m+1)(\lambda D))/(d)-(m\lambda D )/(d)=(\lambda D)/(d)\\\\\Delta y=((500*10^(-9)nm)(5m))/(1*10^(-3)m)=2.5*10^(-3)m=0.25cm](https://img.qammunity.org/2021/formulas/physics/college/lesd5o091p8wziz3pvkx3pqefumu0r8o01.png)
hence, the aswer is 0.25cm