Answer:
The options are
A. model the formation of an igneous rock
B. observe and describe a volcanic eruption
C. collect and test rock specimens
D. perform a controlled experiment on a volcano
The answer is C. collect and test rock specimens
Step-by-step explanation:
The question contains Jill finding evidence that suggests that individuals volcanoes produce igneous rocks with a certain chemical signature.
She also predicts that scientists could use an igneous rock's chemical signature to determine where the rock came from.
The best possible options will be to collect and test the rock specimens to determine the true origin of the rocks under study.