The monument was built in honor of the explorer who was believed _____ the river.

A．to have discovered 　　

B．to have been discovered

C．to discover　　

D．having been discovered

以下哪个产品是因为出险后证据灭失造成责任难以界定，所以被列为产品责任险禁止承保范围。（）

A.汽车防盗装置

B.血液制品

C.电脑软件

D.药品