The infinite geometric series $\sum_{\mathrm{r}=0}^{-} \frac{\mathrm{a}}{\left(\mathrm{y}^{2}-4 \mathrm{y}+5\right)^{\mathrm{r}-\mathrm{l}}}$, where $\mathrm{y}=\mathrm{x}^{2}-6 \mathrm{x}+11$ has a finite sum when $\mathrm{x}$ takes a value
other than
(a) 3
(b) $-1$
(c) 4
(d) $-3$