Consider the transmission of data bits 110001011 over a link that uses Cyclic Redundancy Check (CRC) code for error detection. If the generator bit pattern is given to be 1001, which one of the following options shows the remainder bit pattern appended to the data bits before transmission?

To find the CRC remainder bit pattern:

1. Determine the number of zeros to append: The generator polynomial bit pattern is $G = 1001$, which has a length of $k = 4$ bits. Therefore, we append $(k - 1) = 3$ zeros to the data bits.

2. Append zeros to the data bits: Data bits: $110001011$ Appended bit sequence: $110001011000$

3. Perform modulo-2 binary division:

   • Divide $110001011000$ by $1001$:

   $$\begin{array}{r} 110001011000 \\ \underline{1001\phantom{00000000}} \\ 01010\phantom{0000000} \\ \underline{\phantom{0}1001\phantom{0000000}} \\ 001110\phantom{00000} \\ \underline{\phantom{00}1001\phantom{00000}} \\ 01111\phantom{0000} \\ \underline{\phantom{0}1001\phantom{0000}} \\ 01101\phantom{000} \\ \underline{\phantom{0}1001\phantom{000}} \\ 01000\phantom{00} \\ \underline{\phantom{0}1001\phantom{00}} \\ 000100 \end{array}$$

4. The remaining $3$-bit remainder is $100$.

Thus, the correct option is (D).