Final answer:
The set of data used to make the line plot is lengths of green iguanas.
Step-by-step explanation:
A zookeeper measured the length of green iguanas to chart their growth. She plotted her results on a line plot. The set of data that was used to make the line plot is c) Lengths of green iguanas. This is because the zookeeper specifically measured the lengths of the green iguanas, so these would be the data points used to create the line plot.