Surface$:16(0-15)$ Cylinders$:16384(0-16383)$ Sectors$:64(0-63)$ Size$:512B$
File Size $:42797KB=43824128B$
Currently $:<cylinder,surface,sector> : <1200,9,40>$
In order to complete the current surface we have to go through $24(40,41...63)$ more sectors.
Now address is $: <1200,10,0>$
In order to complete the current cylinder we have to go through $6(10,11...15)$ more surfaces each having $64$ sectors.
How much data is accessed till now $:(24+6\times 64)\times 512B=209408B$
Now address is $: <1201,0,0>$
In order to complete this cylinder we have to go through $16(0,1...15)$ surfaces each having $64$ sectors.
Now look at the options and we are sure that we need to cross $1280^{th}$ cylinder for sure.
How much data is accessed till now $:209408B+((16\times64)\times 80)\times 512=42152448B$
Now address is $: <1281,0,0>$
In order to complete this cylinder we have to go through $16(0,1...15)$ surfaces each having $64$ sectors.
How much data is accessed till now $:42152448B+(16\times64)\times 512=42676736B$
Now similarly you cross $<1282,0,0>$ and $<1283,0,0>$ each having 16 surfaces which in turn have 64 sectors each.
How much data is accessed till now $:42676736B+((16\times64)\times 2)\times 512=43725312B$
It's very close to the file size and if you observe we are currently on the address $<1284,0,0>$ and hence the answer.
Correct Answer $:(D)$