According to Darwin's theory of evolution, what causes a struggle for survival in
populations?

In a population, more individuals are born than can survive. The available resources in nature are finite (food, water, space, etc.) and the environment is not able to support unlimited growth of a population. This causes an inevitable struggle for existence among individuals (continual struggle for existence).

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 for this question would be d. glaciers