Hi Moiz,

Equation 1 is given to us:

Δf = (v/c)*f₀

where v is the velocity of the blood particle, c is the speed of light in a vacuum, and f₀ is the original frequency of the light.

From the universal wave equation, c = fλ for light. We can technically rewrite this using the passage's variables: c = f₀*λ

Subbing in and simplifying, we get

Δf = [v/(f₀*λ)]*f₀

Δf = v/λ

Therefore, there is an inverse relationship between Δf and λ. As λ increases, Δf decreases (but not linearly).

A is the best answer.