Answer:
The answer is A.
Step-by-step explanation:
You have to apply :
[tex] {(a - b)}^{2} ⇒ {a}^{2} - 2ab + {b}^{2} [/tex]
So for this question :
[tex] {(3a - b)}^{2} [/tex]
[tex] = {(3a)}^{2} - 2(3a)(b) + {(b)}^{2} [/tex]
[tex] = 9 {a}^{2} - 6ab + {b}^{2} [/tex]
