A cation is a positively charged ion.
An anion is a negatively charged ion.
If it's neutral, it's just an ion.
Explanation:
We know that,
1 mile = 1609.34 m
We need to find how many meters are present in the 12.45 miles. To find it use unitary method as follows :
12.45 mile = 1609.34 × 12.45
12.45 mile=20036.283 meters
or

Hence, this is the required solution.
The answer should be A.
Hope this helps :-)