Which of the following is the most complex level of hierarchical abstraction currently recognized by synthetic biology open language (sbol)?
a. dna
b. part
c. device
d. system
e. organism

System Explanation:  According to SBOL, a System is a set of devices that cannot be functionally combined with other devices via a common, standard signal, while a Device is a set of parts that can be functionally combined with other devices via a common, standard signal carrier.  A given Part is a a sequence of DNA with a specific function that can be physically combined with other parts via an assembly standard. FInally, DNA comprises a sequence of nucleotides.  As one can see, to build a system it is required first to have a Device built, and to do so we need in turn a Part, the latter containing itself a DNA sequence. Thus, it is clear the composition model where the hierarchical abstraction goes from DNA (less complex) to System (most complex) .  

Although i don't know what is the simulated system, starfish are predators that eat mostly  microalgae,  snails, sponges, bivalves, mussels and other small marine animals. removing starfish from any system would definitely increase this animals that they prey.