[A] : Haversian canals are inter connecting canals that run usually longitudinally through dense bone of vertebrates.
[R]: They contain nerves and blood vessels, each canal serving a series of concentric Iamellae
A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false