**Category:** Inorganic Chemistry  
**Subtype:** Chemical Reactions  
**Problem Description:** Determine how many substances in the given list are oxidized when they react with concentrated, hot sulfuric acid (\(\mathrm{H}_{2} \mathrm{SO}_{4}\)).  

**Substances to Analyze:** \(\mathrm{FeO}, \mathrm{Fe}(\mathrm{OH})_{2}, \mathrm{FeSO}_{4}, \mathrm{Fe}_{3} \mathrm{O}_{4}, \mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}, \mathrm{Fe}_{2} \mathrm{O}_{3}\)  
**Options:** A. 3, B. 5, C. 4, D. 6.