Question

a national database has been established in order to help identify the source of what plants?
poisonous
marijuana
endangered species
pollen

Explanation:

National databases are often established for marijuana to help identify its source for law - enforcement and regulatory purposes such as tracking illegal cultivation and distribution. Poisonous plants may have local or regional databases, endangered species databases focus on conservation rather than source - identification in the same context, and pollen databases are mainly for ecological or allergy - related research.

Answer:

B. marijuana