1. The problem asks to find the sixth term of the expansion of $ (c + d)^{10} $. 2. The general term in the binomial expansion of $ (a + b)^n $ is given by: $$ T_{k+1} = \binom{n}{k} a^{n-k} b^k $$ where $k$ starts from 0. 3. For the sixth term, $k = 5$ (since the first term corresponds to $k=0$). 4. Substitute $n=10$, $a=c$, $b=d$, and $k=5$: $$ T_6 = \binom{10}{5} c^{10-5} d^5 = \binom{10}{5} c^5 d^5 $$ 5. Calculate the binomial coefficient: $$ \binom{10}{5} = \frac{10!}{5!5!} = 252 $$ 6. Therefore, the sixth term is: $$ 252 c^5 d^5 $$ 7. Comparing with the options, this matches option A: $210c^5d^5$ is incorrect, option B and C have wrong coefficients or powers, option D is $252c^5d^5$ which is correct. Final answer: D