A scientist records the count rate of a radioactive sample in a laboratory across 12 weeks. The background radiation count rate in the laboratory stays constant at $20$ counts per minute. The table presents the scientist’s results before the background radiation count rate is allowed for. Within which interval does the half-life of the radioactive isotope fall?
- Abetween 4 and 6 weeks
- Bbetween 6 and 8 weeks
- Cbetween 8 and 10 weeks
- Dmore than 12 weeks