A. color: red, text-decoration: underline and font-style: italic all works
B. text-decoration: underline and font-style: italic works
C. color red, text-decoration: underline works
D. only font-style: italic works

Solution

D. only font-style: italic works

Explanation

hear the ; missing after the first property so only italic property will work. to apply all given property code must be like this:

h1 {color: red; text-decoration: underline; font-style: italic;}