Which of the following vectors is perpendicular to $a = (1, 2, 3)$ and $b = (1, -1, 2)$?

A. $(7, 1, -3)$
B. $(-7, -1, 3)$
C. $(7, -1, -3)$
D. $(1, -2, 6)$
E. $(5, -5, 10)$
F. at least two of the above
G. none of the above