If the four lines are extended, which system would have only one solution?

a line a and line b
b line b and line c
c line b and line d
d line c and line d

A line a and line b

Step-by-step explanation:

Lines b and c are parallel (no intersection points), so the system will have no solutions.

Lines b and d are parallel (no intersection points),  so the system will have no solutions.

Lines c and d coincide (infinitely many intersection points),  so the system will have infinitely many solutions.

Lines a and b will intersect after extension, so the system of these two equations will have only one solution.

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step-by-step explanation: