Answer:
It's changeable
Before the microscope, Linnaeus classified organisms only separated in two kingdoms, while more were introduced later. So, they were only classified in two kingdoms, they can be changed and classified to more than two.
The answer would be chromosomes
Dr. Charles is using fMRI when she uses strong magnets to track changes in the brain's blood-oxygen levels.
Functional magnetic resonance imaging or (fMRI) is a techique used to measure brain activity by detecting changes associated with blood flow. When an area of the brain is in use, blood flow to that region will increase.