Consider a disk with the following characteristics $($these are not parameters of any particular disk unit$)$: block size B $=4096$ bytes; interblock gap size G $=1024$ bytes; number of blocks per track $=50$; number of tracks per surface $=800.$ A disk pack consists of $10$ double$-$sided disks. What is the useful capacity of a track?

$204,800$ bytes

$256,000$ bytes

$204,800,000$ bytes

$327,680,000$ bytes