Answer:
Avoid using their own students in their research in the first place
Explanation:
Due to high amount of interaction that they might possess, the students might form some sort of personal relationships with members of the researchers team.
When this happen, there would be a motive for the students to behave exactly in a way that the researchers want and make the research become invalid.
Answer:
b. temperature
Explanation:
because when it gets cold matter freezes and when matter gets warm it melts
By studying the fossil record we can tell how long life has existed on Earth, and how different plants and animals are related to each other. Often we can work out how and where they lived, and use this information to find out about ancient environments. Fossils can tell us a lot about the past.