Which sentence below best expresses the essential information in the highlighted sentence in paragraph 1? Incorrect choices change the meaning in important ways or leave out essential information.
A.
Every science has a unique set of systems with characteristics and relationships that do not exist in any other science.
B.
The subject matter of systems is the same for all sciences, but the structure of system relationships can vary.
C.
System components and relationships differ for each science, yet systems in all sciences share similar properties.
D.
It is difficult to distinguish one system from another because all systems in all sciences have similar characteristics.