Given f(x)=x^2+4x+7 .

What equation shows function f written in vertex form?

a)​ f(x)=(x+2)^2+3 ​

​ b)f(x)=(x+4)^2+11 ​

c) f(x)=(x+3)^2+7

d) f(x)=(x+4)^2−7