Solution: According to the meaning of the question, A(0, -a), F (0, c), B 1(-b, 0), B2(b, 0), B2 is the midpoint of AP.

AB2 equation

x

b

-

y

a

= 1, that is

Ax times ab=0

① B 1F equation

x

-B.

+

y

c

= 1, that is

cx-by+bc=0

②,

The coordinates of point P can be obtained by combining ① and ② simultaneous equations (

b(a+c)

alternating current

2ac

alternating current

),

According to the midpoint formula, 2b=0+

b(a+c)

alternating current

，0=-a+

2ac

alternating current

∴a=3c，

∴e=

c

a

=

1

three

.

So I chose the answer.

D