A polynomial is in standard form when its terms are arranged in descending order of their degrees (the highest power of the variable comes first).
Let's analyze each option:
A.
Terms are arranged as () (degree 7), () (degree 4), (-x) (degree 1), and (9) (degree 0).
Standard form (terms are in descending order).
B.
Terms are arranged as () (degree 4), (-x) (degree 1), () (degree 7), and (9) (degree 0).
Not in standard form (highest degree term is last).
C.