Which of the following expressions are perfect-square trinomials? Choose two correct answers.
A$x^2+4 x+16$
B$x^2-16 x-64$
C$x^2+20 x+100$
D$4 x^2+12 x+9$
A$x^2+4 x+16$
B$x^2-16 x-64$
C$x^2+20 x+100$
D$4 x^2+12 x+9$