△ABC中,∵B(-2,0),C(2,0),A(x,y),
∴BC=4,
AB =(-2-x,-y),
AC =(2-x,-y),k AB=
y
x+2 ,k AC=
y
x-2 ,
①△ABC的周长为10,即AB+AC+BC=10,而BC=4,所以AB+AC=6>BC,
故动点A的轨迹为椭圆,与b对应;
②∠A=90°,故
AB •
AC =(-2-x,-y)(2-x,-y)=x 2+y 2-4=0,与a对应;
③k ABk AC=1,故
y
x+2 •
y
x-2 =1 .即x 2-y 2=4,与c对应.
故选B.