TOEFL Listening: ETS-TOEFL听力机经 - 63TY296A33JJS8H1P$

Why is the ground squirrel's strategy used only for against rattlesnakes? A. Rattlesnakes can sense heat better than gopher snakes can. B. Rattlesnakes are larger than gopher snakes. C. Gopher snakes have better vision than rattlesnakes. D. Gopher snakes are much less aggressive than rattlesnakes