What should the permission settings be for /etc/passwd and /etc/shadow?

What should the permission settings be for /etc/passwd and /etc/shadow?

A.
/etc/passwd: rwrr /etc/shadow: r

B.
/etc/passwd: r /etc/shadow: rwrr

C.
/etc/passwd: rwrr /etc/shadow: rwrr

D.
/etc/passwd: r /etc/shadow: r