The position vectors of vertices A, B and C of triangle ABC are respectively \(\hat{\text{j}}+\hat{\text{k}}, 3\hat{\text{i}}+\hat{\text{j}+5\hat{\text{k}}}\) and \(3\hat{\text{j}}+3\hat{\text{k}}\). What is angle C equal to?
1
\(\frac{\pi}{6}\)
2
\(\frac{\pi}{4}\)
3
\(\frac{\pi}{3}\)
4
\(\frac{\pi}{2}\)