Find a$)$ any critical values and b$)$ any relative extrema.

$f(x)=x^2-4x+6$

a$)$ Select the correct choice below and, if necessary, fill in the answer box within your choice.

A$.$ The critical value$($s$)$ of the function is$/$are $$

$($Use a comma to separate answers as needed.$)$

B$.$ The function has no critical values.

b$)$ Select the correct choice below and, if necessary, fill in the answer box$($es$)$ within your choice.

A$.$ The relative minimum point$($s$)$ is$/$are $$ and there are no relative maximum points.

$($Simplify your answer. Type an ordered pair, using integers or fractions. Use a comma to separate answers as needed.$)$

B$.$ The relative minimum point$($s$)$ is$/$are $$ and the relative maximum point$($s$)$ is$/$are $$

$($Simplify your answers. Type ordered pairs, using integers or fractions. Use a comma to separate answers as needed.$)$

C$.$ The relative maximum point$($s$)$ is$/$are $$ and there are no relative minimum points.

$($Simplify your answer. Type an ordered pair, using integers or fractions. Use a comma to separate answers as needed.$)$

D$.$ There are no relative minimum points and there are no relative maximum points.