The size property contains two numbers separated by comma, and a space. These numbers are . . . . . . . .

width in pixel, height in pixel
height in pixel, width in pixel
height in cm, width in cm
width in cm, height in cm

The correct answer is: A. width in pixel, height in pixel.

The size property contains two numbers separated by a comma and a space. These numbers represent the width and height of the element in pixels. For example, if the size property is set to “100, 200”, then the element will be 100 pixels wide and 200 pixels high.

Option B is incorrect because the height comes first in the size property.

Option C is incorrect because the units are in pixels, not centimeters.

Option D is incorrect because the width comes first in the size property.