The explicit formula of the recurrence relation

$b_1=1,b_2=7,$ and $b_n=7b_{n-1}-12b_{n-2},$ for all $n3,$ is

a$.$

$b_n=-4^n-3^n,$ for all $n1$

b$.$ None

c$.$

$b_n=4^n-3^n,$ for all $n1$

d$.$

$b_n=4^n+3^n,$ for all $n1$