Two rules are written using the same two unknowns, and both have to hold at the same time. What is that pair of rules called?

1. Two or more linear rules built from the same unknowns form a system. 2. The word system carries the requirement that all of the rules are considered together rather than one at a time. 3. Both rules holding at once is exactly that requirement, so option B names it. 4. Nothing here says the rules clash, so option A adds a claim that is not given. _Source: OpenStax College Algebra (CC BY 4.0), Ch 7 "Systems of Equations and Inequalities", section 7.1 Systems of Linear Equations: Two Variables_