In comparison, what method is superior to any other methods mentioned in the passage

A．It has numerous traits in common with the spotted owl.
B．Its population is increasing.
C．It may not survive without special efforts of conservationists.
D．Its role in the chain of evolution has not yet been examined.

A．They became more popular.
B．They were more regulated.
C．They became less honest,
D．They became better produced.