Answer:
The correct option is B.
Explanation:
It is given that the surface area of an oil spill gets 131% larger every day, represented by the function

Where x is number of days.
On the first day, it covered an area of 21 square meters. It means the initial area is 21 square meters.
The function is defined as

Where is initial value and b is growth factor.
It means the function of new area is the product of initial area and increasing area function. The required function is

Therefore option B is correct.