An analog signal having $3 \; \text{kHz}$ bandwidth is sampled at $1.5$ times the Nyquist rate. The successive samples are statistically independent. Each sample is quantized into one of $256$ equally likely levels. The information rate of the source is :
- $3 \; \text{kbps}$
- $72 \; \text{kbps}$
- $256 \; \text{kbps}$
- $9 \; \text{kbps}$