If an active nest with eggs or nestlings is present, you must seek the assistance of a federally permitted migratory bird rehabilitator in removing the eggs or nestlings. The rehabilitator is then responsible for handling them properly.

The statement claims that if an active nest with eggs or nestlings is present, one must seek the assistance of a federally permitted migratory bird rehabilitator to remove them, and the rehabilitator is then responsible for handling them properly. The statement references 50 CFR 21, 21.12 d(10).

50 CFR Part 21 pertains to Migratory Bird Permits. Specifically, 50 CFR 21.12(d)(10) states: "You may not take, possess, import, export, transport, sell, purchase, barter, or offer for sale, purchase, or barter, migratory birds, their parts, nests, or eggs, except as authorized by a valid permit issued pursuant to this part."

The regulation (50 CFR 21.12(d)(10)) prohibits the taking, possession, or disturbance of migratory birds, their nests, or eggs without a valid permit. It does not state that if an active nest is present, you must seek a rehabilitator to remove the eggs or nestlings. In fact, disturbing or removing an active nest is generally prohibited under the Migratory Bird Treaty Act (MBTA) unless specifically authorized by a permit from the U.S. Fish and Wildlife Service (USFWS), and such permits are typically issued only under specific circumstances (e.g., public safety, scientific research, or depredation permits). The primary approach when an active nest is found is usually to avoid the area until the nest is no longer active. Rehabilitators are typically involved in caring for injured, sick, or orphaned birds, not in the routine removal of active nests.

Since the regulation does not mandate seeking a rehabilitator for the removal of eggs or nestlings from an active nest, and such removal is generally prohibited without specific authorization, the statement is false.

The final answer is $\text{b}$