Answer:
The last graph.
Explanation:
According to the question, she will spend just 36 hours on those activities combined, so the shading will be anything less than the diagonal line with a slope of -1.
She spends at least 12 hours running, so the shaded area will be anything above the horizontal line at 12.
She spends at least 12 hours bicycling, so the shaded area will be anything to the right of the vertical line at 12.
The only graph that fits all the conditions is the last graph, with a shaded triangle.
Hope this helps!