The answer would be:
B. Sequence of the bases in DNA molecules.
Here is more about your questions:
DNA contain the instructions of the traits of an organism. Most of the organism have the same DNA but what makes each different is the sequence of the DNA. The sequence gives the instructions for the production of amino acid that will produce, which in turn determines what traits will be passed on or manifested by that individual.
Organ system is the most complex in organization
It makes sense that cell membranes are made of phospholipids because water cant mix in with lipids, so the phospholipids will be able to effectively block out any unwanted water or chemicals suspended in water outside of the cell.
Rarefaction in terms of ecology can be defined as a technique used to assess species richness from the results of sampling.
It allows the calculation of richness of a particular species for a given number of individual samples, and these are based on the construction of rarefaction curves.
Hence, the correct answer is: option A-Creating a representative sample