Which of the following arrangements correctly represents hexagonal...

In hexagonal close packed (hcp) structure, each sphere of third layer lies exactly above the sphere of first layer. Hence, hcp is abbreviated as $A B A B A B \ldots \ldots .$. In cubic close packed (ccp) structre, the spheres of third layer do not come over those of first layer and sphere of fourth layer correspond with those in first layer. Hence, it can be shown as $A B C A B C \ldots . . .$. .