Find All Rational Zeros $$f ( x ) = x ^ { 4 } - 7 x ^ { 3 } + 3 x ^ { 2 } + 21 x - 18$$

Multiple Choice

Find all rational zeros.
- $$f ( x ) = x ^ { 4 } - 7 x ^ { 3 } + 3 x ^ { 2 } + 21 x - 18$$

A) 6,1
B) $- 6,1$
C) No rational zeros
D) $6 , - 1$