When you write an equation, it tells you, that you know what the math problem is and your steps of solving. For example if the math problem was that:
Trina invited 9 girls and 10 boys to her birthday. 2 girls didn't come and 1 boy didn't come. What is the total amount of people that came to Trina's birthday party.
It makes everything clear from a mathematical point , much easier to solve the question in equation form than trying to figure it out from a long word problem
So the question tells to express the expression in your problem where N0 is N-naught and the symbol represent the lower case Greek letter lambda. So the best answer or expression would be that the lambda is the wavelength of the expression. I hope you are satisfied with my answer
Thank you for posting your question here at brainly. Feel free to ask more questions. <span> The best and most correct answer among the choices provided by the question is</span><span>A. Between 0.05 and 0.01 </span> . <span> Hope my answer would be a great help for you. </span>