An analog signal is band limited to 4 kHz. It is sampled at the Nyquist rate and samples are quantized into 4 levels. The quantization levels have probabilities $$\frac{1}{8},\,\frac{1}{8},\,\frac{3}{8}$$  and $$\frac{3}{8}.$$ The information rate of the source is:

A. 15400 bps

B. 4000 bps

C. 14400 bps

D. 16000 bps

Answer: Option C