There are several different hard drives available for a computer. Which one of the following size hard drives is the largest?

A. 1.2 GB
B. 640 K
C. 550 MB
D. 1000 bytes

The largest hard drive size listed is A. 1.2 GB (gigabytes).

To determine which size hard drive is the largest among the given options, we need to compare the values.

A. 1.2 GB: 1.2 gigabytes
B. 640 K: 640 kilobytes
C. 550 MB: 550 megabytes
D. 1000 bytes

To make a comparison, we need to convert all the values to the same unit.

1 gigabyte (GB) = 1024 megabytes (MB)

Now let's convert the values:

A. 1.2 GB = 1.2 * 1024 MB = 1228.8 MB
B. 640 K = 640 kilobytes
C. 550 MB = 550 megabytes
D. 1000 bytes

Comparing the values, we see that the largest hard drive size among the given options is 1228.8 MB, which corresponds to option A. 1.2 GB.