The description on the graph is: (c) after 30 seconds, she turned it down to low for 30 seconds. She turned it back to high for 60 seconds, then turned it off.
From the complete question, we have the following highlights
The graph has three horizontal lines
One of the lines is on the x-axis
The other lines represent high and low, and they have intervals of 30 and 60 seconds, respectively
Hence, the description on the graph is:
After 30 seconds, she turned it down to low for 30 seconds.
She turned it back to high for 60 seconds, then turned it off.
