Answer:
d. 9!
To solve this problem, you can use the permutation formula, which is given by the following:
![$$P_(n)^(r) = (n!)/((n - r)!)$$](https://img.qammunity.org/2023/formulas/mathematics/high-school/n6lvgt31m31jllcl8ajsoc81393q9e6yzp.png)
In this formula,
is the total number of items, and
is the number of items being chosen at a time.
In this case, we have a total of 9 letters in the word WISCONSIN, and we want to rearrange them to form 9-letter strings. Therefore, we can use the permutation formula as follows:
![$$P_(9)^(9) = (9!)/((9 - 9)!) = (9!)/(0!) = 9! = \boxed{362,!880}$$](https://img.qammunity.org/2023/formulas/mathematics/high-school/jbeypmm4pjqd0hxdzrz91ghgrrlj7adxmj.png)
This means that there are 362,880 different 9-letter strings that can be made by rearranging the characters in the word WISCONSIN.