How do scientists know that the universe is expanding?
The Doppler effect shows stars with yellow shifted light
The Doppler effect shows stars with green shifted light
The Doppler effect shows stars with red shifted light
The Doppler effect shows stars with blue shifted light

C. The Doppler effect shows stars with red shifted light.

Explanation: Evidence

Astronomers have discovered that, in general, the further away a galaxy is, the more red-shifted its light is. This means that the further away the galaxies are, the faster they are moving and expanding.

C: The Doppler Effect shows stars with red shifted light

Explanation:

the transfer of energy between two molecules spaced just nanometers apart plays a key role in many technologies, including photovoltaics, quantum information systems, lighting, and sensors, as well as in biophysics to measure nanometer distances and in photosynthesis. but an open question in this area is what effect, if any, the surrounding photonic environment has on this nanoscale energy transfer. by designing and performing a carefully controlled experiment to answer this question, scientists have settled the debate and found clues to improving the efficiency of many of the technologies that rely on this process.

explanation:

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.