Final Answer:
The system that has exactly one solution is B) y = 4x + 9, y = 4x - 9.
Step-by-step explanation:
One Solution Criteria: A system of linear equations has exactly one solution when the lines represented by the equations intersect at a single point.
Analysis of Options:
Option A: The equations in option A are dependent, representing the same line. This results in infinitely many solutions.
Option B: The two lines in option B have different slopes, ensuring they intersect at a unique point. This system has one solution.
Option C: The lines in option C are parallel, indicating no intersection and no solution.
Option D: The lines in option D intersect at a unique point, resulting in one solution.
Option B is the answer.