Answer:
D
Explanation:
The formula we need to solve this is:
![d_1+d_2=2a](https://img.qammunity.org/2020/formulas/mathematics/middle-school/jj070mi7sa27g1uxyunsqkt4zwat4a8avx.png)
Where
is the distance from one focus to the vertex
is the second distance from another focus to same vertex
Note: Here, vertex point is the point on top. The common point from which the RED and BLUE line meets the 2 foci
is half the length of the major axis (which is 9 here since total major axis is given as 18)
Now we can plug into the equation and solve:
![d_1+d_2=2a\\8.5+d_2=2(9)\\8.5+d_2=18\\d_2=18-8.5\\d_2=9.5](https://img.qammunity.org/2020/formulas/mathematics/middle-school/eswuuuqesdfjvjlrp48jqwxfi29jdsr0x3.png)
D is the correct answer.