outline-size
outline-width
outline-height
both a and b
Answer is Wrong!
Answer is Right!
The correct answer is B. outline-width.
Outline-width is a CSS property that specifies the width of an outline. It is a length value, and the default value is 0.
Outline-size is a CSS property that specifies the size of an outline. It is a length value, and the default value is 0.
Outline-height is a CSS property that specifies the height of an outline. It is a length value, and the default value is 0.
Therefore, the only property that specifies the width of an outline is outline-width.