参考答案：A

解析：

The crossover rate is the rate at which the NPV for two projects is the same. That is, it is the rate at which the two NPV profiles cross. At a discount rate of 9%, the NPV of Project A is: CF0=-4; CF1=3; CF2=5; CF3=2; 1=9%; CPT→NPV=$4.51. Now perform the same calculations except that we need to set the unknown CF0=0.The remaining entries are: CF1=1.7; CF2=3.2; CF3=5.8; I=9%; CPT→NPV=$8.73. Since by definition the crossover rate produces the same NPV for both projects, we know that both projects should have an NPV=$4.51. Since the NPV of Project B (with CF0=0) is $8.73, the unknown cash flow must be a large enough negative amount to reduce the NPV for Project B from $ 8.73 to $4.51. Thus the unknown initial cash flow for Project B is determined as $4.51=$8.73+CF0, or CF0=-$4.22.