Combine like​ terms, if possible. Write the result with descending powers. -7x^4 + 4x^4 - 6x^4

Select the correct choice below and fill in the answer box to complete your choice.

A. The polynomial can be simplified. -7x^4 + 4x^4 - 6x^4 =

B. The polynomial cannot be simplified. The polynomial written in descending powers is =