Working through a system by substitution leaves the statement 9 = 13. What does that ending mean?

1. The statement 9 = 13 is false for every possible pair of values. 2. Reaching a false statement by correct working means the starting assumption cannot hold. 3. The assumption was that some pair satisfies both rules, so no such pair exists. 4. A system with no solution is inconsistent, and its lines are parallel. 5. Options B and C read the two numbers as answers, but they are the two sides of a contradiction rather than values of unknowns. 6. Option A belongs to the other ending, an identity such as 0 = 0. _Source: OpenStax College Algebra (CC BY 4.0), Ch 7 "Systems of Equations and Inequalities", section 7.1 Systems of Linear Equations: Two Variables_