For each set of data below, draw a scatterplot and decide whether or not the data exhibits approximately periodic behaviour.

a) $\begin{array}{|cccccccccccccc|}\hline x& 0& 1& 2& 3& 4& 5& 6& 7& 8& 9& 10& 11& 12\\ y& 0& 1& 1.4& 1& 0& -1& -1.4& -1& 0& 1& 1.4& 1& 0\\ \hline\end{array}$

b) $\begin{array}{|cccccc|}\hline x& 0& 1& 2& 3& 4\\ y& 4& 1& 0& 1& 4\\ \hline\end{array}$

c) $\begin{array}{|ccccccccc|}\hline x& 0& 0.5& 1.0& 1.5& 2.0& 2.5& 3.0& 3.5\\ y& 0& 1.9& 3.5& 4.5& 4.7& 4.3& 3.4& 2.4\\ \hline\end{array}$

d) $\begin{array}{|cccccccccccc|}\hline x& 0& 2& 3& 4& 5& 6& 7& 8& 9& 10& 12\\ y& 0& 4.7& 3.4& 1.7& 2.1& 5.2& 8.9& 10.9& 10.2& 8.4& 10.4\\ \hline\end{array}$