Answer:
b. (x + 1) raised to the power of 4.
Step-by-step explanation:
To know the answer, we need to solve the expression of every answer and compare the result with the initial expression.
So, (4x +1) raised to the power of 4 is equal to:

Applying the distributive property, we get:

Therefore, this is not the correct answer:
In the same way, (x + 1) raised to the power of 4 is equal to:

Since this is equal to the initial expression, the correct answer is b. (x + 1) raised to the power of 4.