\(a\) is the hundreds digit of the three-digit integer \(x.\) On the other hand, \(b\) is the tens digit of \(x,\) and \(c\) is the units digit of \(x.\) If \(a = 2b = 4c,\) and \(a > 0,\) what is the difference between the two greatest possible values of \(x?\)

A. 124
B. 297
C. 394
D. 421
E. 842

[spoiler]OA=D[/spoiler]

Source: Veritas Prep