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The magnitude and phase of the complex Fourier series coefficients ܽ$a_{k}$ of a periodic signal $x(t)$ are shown in the figure. Choose the correct statement from the four choices given. Notation: $C$ is the set of complex numbers, ܴ$R$ is the set of purely real numbers, and $P$ ܲis the set of purely imaginary numbers.

1. $x(t)\in R$
2. $x(t)\in P$
3. $x(t)\in (C-R)$
4. the information given is not sufficient to draw any conclusion about $x(t)$