Ascientist suspects that food in an ecosystem may have been contaminated by radioactive nitrogen over a period of several months. which of the following should be isolated from mammals living in the ecosystem and examined for radioactivity in order to test the hypothesis?

Hair

Explanation:

The scientist predict that the contamination occurred several months ago. Under normal circumstances, most organisms would no longer have a trace of exposure in their urine or blood after 3 months.  If the organisms exposed to the radioactive three months ago and do not come near that area again within 3 months, the scientist wouldn't be able to identify it.

But, if that substance got into their hair, it will last way longer than that. Hair Analysis is very common to be used among forensic toxicologist to identify contamination that occurred months because of this.

answer; criterion validity