Final answer:
The best definition of a linear inequality is a mathematical statement that compares two unequal expressions using inequality symbols.
Step-by-step explanation:
The best definition of a linear inequality is D. A mathematical statement that compares two unequal expressions. A linear inequality is similar to a linear equation, but instead of an equals sign, it uses inequality symbols like <, <, >, or > to show that one side of the inequality is not equal to the other. An example of a linear inequality would be y > mx + b, where m is the slope and b is the y-intercept.