Clifford Attractor

The Clifford attractor is a map defined by two nonlinear equations.

\begin{equation} x_{n +1} = \sin(a y_{n}) + c \cos(a x_{n}) \end{equation}

\begin{equation} y_{n +1} = \sin(b x_{n}) + d \cos(b y_{n}) \end{equation}

The behavior of the attractor changes drastically with the combination of parameters,

A:
B:
C:
D: