[tex]\huge{\boxed{\text{D}}}[/tex]
This line is in the format [tex]y=mx+b[/tex], where [tex]m[/tex] is the slope.
A horizontal line has a slope of [tex]0[/tex].
A vertical line has an undefined slope.
A positive slope makes the line go upwards and to the right.
A negative slope makes the line go downwards and to the right.