The memory allocation scheme subject to "external" fragmentation is

ANS:A - segmentation

External fragmentation means: suppose you have memory block available of 100mb and you have 3 tasks of say 1st 5mb, 2nd 4mb and 3rd 10mb. But remember although you have 100mb but you can give that memory block to any one of them.

So simple you have to broke that memory block means to make a segment of say 20mb segment size.

So remember now you have 5 segments of 20mb n you can store 5 different data of size up to 20 MB.