In this task, you are given a question and answer for that. The answer will fill in the blank or will complete the unfinished question. Your task is to provide an explanation based on the given question or fill-in-the-blank statement, and answer.

[EX Q]: Question: Sarah ate a piece of shark meat for dinner, Sarah's levels of toxic metals have 
 Answer: increased or
[EX A]: The higher up a food chain that humans eat, the greater the levels of toxic metals they take in.

[EX Q]: Question: When we lower the temperature of water it becomes 
 Answer: more dense
[EX A]: When a volume of water is cooled, the molecules move less vigorously, so same number of molecules takes up less space and the water is denser.

[EX Q]: Question: As we dig deeper into rocks they get 
 Answer: older
[EX A]:
Lower rock layers were laid down earlier, so they are assumed to contain older fossils.