Step 1: Concept
The sum of binomial coefficients is $\sum_{r=0}^{n} {}^nC_r = 2^n$.
Step 2: Analysis
The expression is ${}^{100}C_0 + {}^{100}C_1 + {}^{100}C_2 + \dots + {}^{100}C_{99} + {}^{100}C_{100}$.
(Note: $1 = {}^{100}C_0$ and $1 = {}^{100}C_{100}$).
Step 3: Conclusion
This is the complete sum of coefficients for $n = 100$.
Sum $= 2^{100}$.
Final Answer: (D)