Evaluate the expression. Round the answer to the nearest whole number.
\[
{ }_{12} \mathrm{C}_{6}
\]
A. 924
B. 665,280 .
C. 332,640
D. 1,440

Step 1 ：The problem is asking for the combination of 12 items taken 6 at a time. This is a common problem in combinatorics and can be solved using the combination formula which is given by: \(C(n, k) = \frac{n!}{k!(n-k)!}\) where n is the total number of items, k is the number of items to choose, and '!' denotes factorial.

Step 2 ：In this case, n = 12 and k = 6. So we need to calculate: \(C(12, 6) = \frac{12!}{6!(12-6)!}\)

Step 3 ：The calculation gives us the combination of 12 items taken 6 at a time and rounds the result to the nearest whole number. The result is 924, which matches option A in the question.

Step 4 ：Final Answer: \(\boxed{924}\)