The United Nations Has Established a Network of Biosphere Reserves

The United Nations has established a network of Biosphere Reserves, each of which consists of a:

A) core reserve.
B) core reserve and buffer zone.
C) core reserve, buffer zone, and transition area.
D) core reserve, buffer zone, transition area, and remediation zone.
E) core reserve, buffer zone, transition area, remediation zone, and education center.