heavy metals threaten some forms of life. heavy metals will increase available resources. exposure to heavy metals causes healthy mutations. mining for heavy metals causes environmental stability.
I gave my students this multiple choice question: Scientists are concerned about the presence of heavy metals like lead and mercury in the environment because

Only one answer is correct among these 4 choices:
- heavy metals threaten some forms of life.
- heavy metals will increase available resources.
- exposure to heavy metals causes healthy mutations.
- mining for heavy metals causes environmental stability.

Could you tell me which one is correct?

heavy metals threaten some forms of life.