Final answer:
The system with 2 equations in 5 unknowns may have infinitely many solutions if it is consistent. The correct statement is 'if the system has a solution, the family of solutions must have at least 3 parameters' because the solution space can be described by at least three free variables. Option c.
Step-by-step explanation:
In the given scenario, a system of linear equations has 2 equations in 5 unknowns.
According to linear algebra, if the number of unknowns exceeds the number of equations, the system does not have enough constraints to determine a unique solution. In this case, the system may have infinitely many solutions, depending on the consistency of the equations.
Therefore, statement (c) 'if the system has a solution, the family of solutions must have at least 3 parameters' is true. This implies that the solution space can be described by at least three free variables, or parameters, which define a family of solutions.
So Option c.