To solve this question, you would need to do order or operations, also knows as PEMDAS. PEMDAS stands for:
P- parenthesis
E- exponents
M/D- multiplication/division (these are on the same level, and you do them from left to right)
A/S- addition/subtraction (these are on the same level, and you do them from left to right)
So, looking at the equation, you first want to look for parenthesis. If there are no parenthesis present, you move on to exponents.
If there are parenthesis, which in this equation there is, you do whatever is in the parenthesis, using PEMDAS. So, using PEMDAS, we see that inside the parenthesis is an exponent. So, you would do the exponent.
Thus, your answer would be B, 4^2
Hope this helps :)