Are there options, because I believe the answer is D.
Complete Question
The complete question is shown on the first uploaded image
Answer:
The wavelength is
Explanation:
From the question we are told that
The distance of the slit to the screen is 
The order of the fringe is m = 6
The distance between the slit is
The fringe distance is 
Generally the for a dark fringe the fringe distance is mathematically represented as
![Y = \frac{[2m - 1 ] * \lambda * D }{2d}](https://tex.z-dn.net/?f=Y%20%20%3D%20%5Cfrac%7B%5B2m%20%20-%201%20%5D%20%2A%20%20%5Clambda%20%2A%20%20D%20%20%7D%7B2d%7D)
=> ![\lambda = \frac{Y * 2 * d }{[2*m - 1] * D}](https://tex.z-dn.net/?f=%5Clambda%20%20%3D%20%20%5Cfrac%7BY%20%2A%20%202%20%2A%20%20d%20%7D%7B%5B2%2Am%20%20-%20%201%5D%20%2A%20%20D%7D)
substituting values
=> ![\lambda = \frac{0.019 * 2 * 0.9*10^{-3} }{[2*6 - 1] * 5}](https://tex.z-dn.net/?f=%5Clambda%20%20%3D%20%20%5Cfrac%7B0.019%20%2A%20%202%20%2A%20%200.9%2A10%5E%7B-3%7D%20%7D%7B%5B2%2A6%20%20-%20%201%5D%20%2A%20%205%7D)
=> 

Equilibrium implies that the net force on the body is 0, therefore the body undergoes no acceleration. No acceleration means the velocity doesn't change.
The body's velocity stays constant over time.
Drier air Overland then water BR &/BR are the answers so the second one the second I’m in the first option