Answer:
B. 5x + 12.
Explanation:

Whenever you see variables without a visible coefficient, imagine there is a '1' in front of the variable.

From here, you can combine like terms.
Remember, combine means to add.
Like terms are terms whose variables (such as x or y) with any exponents are the same (such as x² or y²).



I, therefore believe 5x + 12 is equal to 4 + x + x + 2x + 5 + 3 + x.