Given Fragment offset = 300, M = 0 So Last Fragment
For Fragment offset scaling factor is 8 so Total 300*8= 2400B ahead of Last fragment which are ranging from (0 to 2399)
So Last Fragment seq no starts from 2400
Now Given Total length = 400B In this Header size = 10*4=40B (Scaling factor of IP Header = 4)
Data = Total length - header length = 400-40 =360B
So Sequence number of last byte = 2759
Option C