Which of the following IS NOT one of the key aspects of systems?

	a.	The value of a system is found in the interactions and relationships between its parts
	b.	All systems are composed of sub-systems and are also situated within higher level super-systems
	c.	Every system has at least one boundary
	d.	Many of the challenges we face today stem from systems failures and therefor a systems view is required to solve them
	e.	Systems are rarely found in nature, but are a key component of man-made environments