Let ƒ(x)=−x2+6x−10. Which statement is true regarding the function ƒ(x)?
f(x)=−(x−3)2+1 the function has a minimal value of 1

f(x)=−(x−3)2+1 the function has a maximum value of 1

f(x)=−(x−3)2−1 the function has a minimal value of−1

f(x)=−(x−3)2−1 the function has a maximum value of −1