Answer: Option d) 33
$8GB = 8*2^{30}B = 2^{33}B$, hence $33$ address lines are required to address $8GB$ memory.
@Jeetmoni saikia Oh this is due to:-
1K (kilo) = 2^101M (mega) = 2^201G (giga) = 2^301T (Tera) = 2^401P (Peta) = 2^501E (Exa) = 2^60