Evaluate the expression.
\[
{ }_{10} \mathrm{P}_{3}
\]
A. 720
B. 27
C. 120
D. 7

Step 1 ：The given expression is a permutation, which is a way of arranging items where the order is important. In this case, we are asked to find the number of ways to arrange 3 items out of 10.

Step 2 ：The formula for permutations is: \(nPr = \frac{n!}{(n-r)!}\) where n is the total number of items, r is the number of items to choose, and ! denotes factorial, which is the product of all positive integers up to that number.

Step 3 ：So, we need to calculate 10P3 using this formula.

Step 4 ：Let n = 10 and r = 3.

Step 5 ：Substitute the values into the formula, we get \(10P3 = \frac{10!}{(10-3)!}\).

Step 6 ：Evaluating the expression, we get the result as 720.

Step 7 ：Final Answer: \(\boxed{720}\)