我国的城市合作银行实际是( )商业银行。

A．国家独资

B．合伙制

C．股份制

D．合作制

For hundreds of years, pearl divers have gathered pearls directly from mollusks on the seafloor. This is an extremely risky profession, exposing the divers to risks of drowning, air embolism, and shark attacks. Still, as long as society demands authentic cultured pearls, these brave divers must continue to risk their lives.
Which of the following statements, if true, most seriously weakens the conclusion above ？（）

A. Shark attacks on pearl divers have decreased steadily over the last three decades because of declining shark populations.

B. Cultured pearls are generally considered more beautiful than those made by artificial means.

C. Robotic pearl harvesters can gather pearls faster and at less cost than human divers, although they may disturb aquatic communities.

D. Part of the value of cultured pearls derives from the exotic way in which they are obtained.

E. With the proper equipment and training, a diver employing scuba gear can harvest three times as many pearls per hour as can a free air diver.