The main characteristic of scientific research is :

The correct answer is D. All of the above.

Scientific research is empirical, theoretical, and experimental.

• Empirical means that scientific research is based on observation and experimentation. Scientists collect data and evidence to support their hypotheses and theories.
• Theoretical means that scientific research is based on a set of assumptions and principles. Scientists use these assumptions and principles to explain the data they collect.
• Experimental means that scientific research is based on the testing of hypotheses. Scientists design experiments to test their hypotheses and collect data to support or refute them.

All three of these characteristics are essential for scientific research to be valid and reliable.