If a permutation σ is given by line 1: (1, 2, 3, 4, 5, 6, 7, 8, 9) and line 2: (3, 1, 4, 2, 8, 6, 9, 7, 5), then the order of σ is:

In the polynomial ring &mathbb;Q[x], if f(x) = x3 + x2 + x + 1 and g(x) = x3 - x2 + x - 1, then the ideal ⟨f(x), g(x)⟩ generated by f(x) and g(x) is equal to:

Which of the following algebraic structures forms an Abelian group under the usual operation?