Theory because a theory is a well substantiated explanation of how a particular phenomenon works based on the set of facts which had been repeatedly confirmed through observations and experiments. A scientific theory gives reliable account of a phenomenon.
The basic research is a type of research that mainly aims to increase the existing base of the scientific knowledge and hence, in the case of psychology the basic research would increase the knowledge about psychology.
Therefore, the purpose of basic research is to add up to the knowledge that already exists.
The research that is conducted to especially solve certain problems or answer specific questions is called applied research. Its main aim is to find out the solution for a given problem.
Therefore, in the case of psychology applied research is conducted to explore practical problems.
3) they lose energy at a varying rate - is the correct answer.
Radioactive decay is defined as the process by which an unstable atomic nucleus loses its energy by emitting radiations. The decay is random and cannot be predicted earlier.
