Question: Maria collected the gas given off by a glowing piece of charcoal. The gas was then bubbled through a small amount of colorless limewater. Part of Maria's report stated, "After the gas was put into the jar, the limewater gradually changed to a milky white color." This statement is

  Options: 
 A. an observation
 B. a conclusion
 C. a generalization
 D. an assumption of the investigation
Answer: A