MO640 - Multiple-choice question

Regarding Norm properties, about permutations in Genome Rearrangements, which of the following properties is NOT true:

a - ||α|| = 0 if and only if α = 1
b - ||αβ|| ≤ ||α|| + ||β||
c - ||αβ|| = ||βα||
d - ||α|| = |E| - |orb(α)|
e -  None of above