Correct Answer - Option 3 : 4 GB
Concept:
1 GB = 1024 MB
1 MB = 1024 KB
1 KB = 1024 B
1 B = 8 bits
So, 32-bit address bus has access to 232 locations with 8 bits(1 Byte) of information.
232 locations = 22 * 210 * 210 * 210 locations
232 locations = 22 * 210 * 210 * 1024 bits
232 locations = 22 * 210 * 1024 Kbits
232 locations = 22 * 1024 Mbits
232 locations = 4 Gbits of location containing 8 bits(1 Byte) of information.
Therefore, 4 Gbits * 8 bits = 4 GB
Correct Option is 3