两电阻R₁、R₂并联时总电阻为4Ω，接入电路中时，它们通过的电流I₁：I₂=1：2，则R₁、R₂的阻值分别为（　　）

A．1Ω，3Ω

B．2.7Ω，1.3Ω

C．6Ω，12Ω

D．12Ω，6Ω

Why are the private lands surrounding Glacier National Park so important

A．They function as a hunting preserve.

B．They are restricted to government use.

C．They are heavily populated.

D．They contain natural habitats of threatened species.