Consider a project with four activities: A, B, C and D. Assume A can be started as soon as the project is kicked off. B and C can both start as soon as A is completed (B and C can happen simultaneously). D can start as soon as both B and C are completed. Which of the following choices is the correct collection of immediate precedence relationships in the project network?

	a.	A--> B, B --> C, C--> D
	b.	A-->B, A--->C, B--->C, C-->D
	c.	A-->B, A--->C, B--->C, B-->D, C--->D
	d.	A-->B, A--->C, B--->D, C--->D