an explanation to a problem, which can be tested scientifically through an investigation is known as what ?

A theory.   Theories explain a phenomnon while laws state a phenomenon but do not explain them.  Ex: Theory of evolution by Darwin explains how evolution works, while the law of thermodynamics states what occurs, but offers no interpreation of its meaning.

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:

oxygen +1 most likely