Given:
The equation of ellipse is

To find:
The length of the minor axis.
Solution:
The standard form of an ellipse is
...(i)
where, (h,k) is center, if a>b, then 2a is length of major axis and 2b is length of minor axis.
We have,
...(ii)
On comparing (i) and (ii), we get

Taking square root on both sides.

Consider only positive value of b because length cannot be negative.

Now,
Length of minor axis = 
= 
= 
So, the length of minor axis is 8 units.
Therefore, the correct option is B.
55 min/10 km=5.5 min/km
5.5 min/km x 1 km/.621 mile= 5.5/.621=8.86 min/mile
The answer is D.
It’s B I did this question and got the same answer