Final answer:
The correct statement is that a system of equations consists of two or more equations that must be true at the same time. These equations can represent various types of relationships, not exclusively linear ones.
Step-by-step explanation:
The true statement among the provided options is: A system of equations consists of two or more equations that must be true at the same time. It doesn't necessarily contain only linear equations, as they can be of any kind as long as they satisfy the condition of being true together.
Equations are representations of truths that express our understanding of a relationship or a problem. When we have multiple variables affecting an outcome, we may need more than one equation to establish this relationship—hence the need for systems of equations. In the context of linear relationships, a linear equation is typically of the form y = mx + b. To solve a system with multiple unknowns, we typically need the same number of equations as there are unknowns.