For \(f\left( z \right) = \frac{{{z^2}}}{{{z^2} + {a^2}}}\), which of the following conclusions is/are correct?
1
z = ia is a simple pole of f(z)
2
z = ia is not a simple pole of f(z)
3
\(\frac{1}{2}ia\) is a residue at z = ia of f(z)
4
\(\frac{1}{3}ia\) is a residue at z = ia of f(z)