(i.e \(en\) and \(C_2O_4\) ), so coordination number of \(E\) is \(6\)
\((2 \times 2 + 1 \times 2 = 6)\)
Let the oxidation state of \(E\) in complex be \(x\), then
\([x + (-2) = 1]\) or \(x -2 = 1\)
or \(x = + 3\), so its oxidation state is \(+ 3\) Thus option \((d)\) is correct.