The amount of DNA present in the system of an organism that does not necessarily relate to how complex that certain organism is. There are single-celled microorganism with very few amount of DNA but are very complex with respect to arrangement of certain amino acid component of the DNA strands.
If ecology is an option than it is that.
The best answer is b - experiment.
An organized process that is used to gather and analyze observations and test a hypothesis is an experiment.
An experiment is the fourth step in scientific method after observation, question and hypothesis.
An experiment is a test that is carried out under controlled conditions with the purpose of demonstrating a known truth, determine the efficacy of a yet untried thing or to examine the validity of a hypothesis.
A hypothesis is a proposed solution for an occurrence that is still unexplained and which does not fit in current accepted scientific theory.
The small intestines have a protective lining that is resistant to acids
