Using the doppler effect, astronomers can determine the
frequency of light, f(v), in terahertz (THz) emitted from
a galaxy with a velocity in the direction toward Earth of v,
as a fraction of the speed of light c. It is true that galaxies
with a velocity of 0 toward Earth emit light with a positive
frequency, and frequency is never 0 THz for any velocity.
Additionally, as the velocity toward Earth increases, the
frequency of light emitted increases. Which of the
following could represent the graph of y = f (v) in the
vy-plane?