If $( \overrightarrow a \: and \: \overrightarrow b)$ are two vectors such that $( | \overrightarrow a. \overrightarrow b| = | \overrightarrow a x \overrightarrow b |)$, then what is the angle between $( \overrightarrow a \: and \: \overrightarrow b)?$

Question

$\begin{array}{1 1}\text{a. $\theta = 4$} \\ \text{b. $\theta = n$} \\ \text{c. $\theta = \frac {4}{n}$} \\ \text{d. $ \theta = \frac {n}{4}$} \end{array} $