A function is defined by the equation y=x²+5x+4. Which statements are true?

A. The graph of the function has a minimum of y=- 9/4 at x=- 5/2 .
B. The equation written in vertex form is y=(x+ 5/2 )²- 9/4 .
C. The graph of the function has a minimum of y=- 9/4 at x= 5/4 .
D. The range of the function is all real numbers.