Chapter 4, Problem 20RQ

Which of the following C# expressions results in TAX being added to price if the integer itemNumber is not 100?

1. $\begin{array}{l}\text{if}\left(\text{itemNumber}!=100\right)\\ \text{price}=\text{price}+\text{TAX};\end{array}$
2. $\begin{array}{l}\text{if}\left(\text{itemNumber}==100\right)\\ \text{price}=\text{price}+\text{TAX};\end{array}$
3. $\begin{array}{l}\text{if}\left(\text{itemNumber}<100\left|\right|\text{itemNumber}\text{>}\text{100}\right)\\ \text{price}=\text{price}+\text{TAX};\end{array}$
4. all of these