Answer:
A. 
Step-by-step explanation:
Given:
The regular polygon is a decagon having 10 sides.
Perimeter of the given polygon is,
.
We know that, perimeter of a regular polygon of
sides is given as,
where,
is the length of each side.
Here, 
Plug in these values and solve for
. This gives,

Therefore, the side length of the given polygon is 