The Wavelength $\lambda$ ₀ of Light Emitted by a Moving Object Is Detected

The wavelength $\lambda$ ₀ of light emitted by a moving object is detected as a different wavelength $\lambda$ by a stationary observer. If v is the velocity of the object and c is the velocity of light, this Doppler shift can be described by the equation

A) ( $\lambda$ - $\lambda$ ₀ = v - c.)
B) ( $\lambda$ / $\lambda$ ₀ = v/c.)
C) ( $\lambda$$\lambda$ ₀ = vc.)
D) ( $\lambda$ - $\lambda$ ₀) / $\lambda$ ₀ = v/c.)