Final answer:
HBr is the strongest acid among the given options because it is a strong acid that readily donates its proton, which is a characteristic of strong acids according to the Brønsted-Lowry definition.
Step-by-step explanation:
The compound that is the strongest acid among the given options is HBr (hydrobromic acid). Analyzing the strength of acids involves understanding their tendency to donate a proton in a solution. According to the Brønsted-Lowry definition of acids, those substances that donate protons are considered acids. HBr is a strong acid, similar to other halogen acids like HCl and HI, because it readily donates its proton to water and ionizes completely in aqueous solution. Factors such as electronegativity and the number of attached oxygen atoms influence the strength of an acid. As Br is less electronegative compared to elements like F in HF, HBr is less polar and more readily donates its proton, making it a stronger acid. Moreover, compared to other options such as H₂S, Li₂O, and LiB, which are not recognized as strong acids, HBr stands out as the strongest among them.