<span>All natural radiation is at a level low enough to be safe</span>
Answer:
Controlled group does not receive the treatment. It used as a benchmark to measure how different tested subjects affected the result of the experiment.
For example, the famous experiment of whether plants grow faster with music in one room and without music in the other room. The plant in the no music room is the controlled group.
Answer:
Ginkgo
Explanation:
Ginkgo improves memory and enhance circulation and metabolism in the brain.
Batteries cause problems in all BUT one way. That is
radiation. If batteries come to its expiration date, its chemicals, especially
the harmful ones will spread in the atmosphere and create pollution to its
environment. That is the reason why it is wrong to dispose batteries
everywhere.