Answer:
a. Exposure to electromagnetic fields is known to cause leukemia.
Step-by-step explanation:
According to various scientific research, it has been revealed that "Exposure to electromagnetic fields has no direct effect or cause for leukemia in humans."
However, it has been proven that excessive asbestos exposure can lead to asbestos is with symptoms such as shortness of breath, coughing, etc.
Similarly, excessive exposure to radiation like gamma rays, X-rays can cause health problems including cancer.
Also, based on research 70 dB sound is considered ideal, and any sound above 80 dB is potentially dangerous.