B. is the correct sentence, because they use the correct verb tense of notices.
B. However, is the correct answer.
Answer:
The majority of background radiation occurs naturally from minerals and a small fraction comes from man-made elements. Naturally occurring radioactive minerals in the ground, soil, and water produce background radiation. The human body even contains some of these naturally-occurring radioactive minerals
Explanation:
Answer:
it means things are gonna get harder
Explanation: