Answer:
Graph given on the top right side.
Step-by-step explanation:
Nina used 5 L of water from her rain barrel to water her plants every week.
She did this until her rain barrel was empty.
So barrel will be empty in the time = weeks.
Nina started watering when rain barrel contained 75L of water.
We draw a graph with water remaining on y-axis and weeks to get the barrel empty on x-axis.
Line representing this process will start from a point (0, 75) on y-axis and will end at x-axis at the point (15, 0).
Therefore, graph given on the top right side of the options is the correct answer.